To revert, you will need to DL and install 3.1.2 firmware. You will get stuck in a recovery mode loop that will try and force you to update back to 3.1.3. iTunes will also move your 3.1.2 FW file to the trash w/out asking you. After downgrading, you will need to run the iRecovery software to set your iPhone's autoboot functionality to boot out of recovery mode.

http://www.ihackintosh.com/2009/07/irecovery-iphone-recovery-mode-loop-restart/

It all works, but a major PITA. Steer clear 3.1.3 until the official JBs are out again, which most like will not be until 4.0.

It's more dangerous than just temporarily losing your jailbreak- because the upgrades can include more than just a firmware upgrade. A perfect example is the 3.1.2 (IIRC) update, which also updated the baseband, making it impossible to re-jailbreak for quite a while (even after the upgrade was available to those with jailbroken phones). Once it was finally jailbroken, it was a tethered jailbreak, which meant that every time you booted your iphone, it had to be connected to your computer & blackra1n. Luckily the incredible hackers who bring us the jailbreak figured out a way around that and now it's fine.

The preferred method to update is to download a pre-jailbroken firmware file, and update through iTunes using that. Then you don't have to go through the process of jailbreaking again, since it comes that way when you upgrade. You also won't have to worry about any type of other issues (like baseband upgrades).

Thanks for the great recommendations. The ProSwitcher app is a nice alternative to Backgrounder and I really like all of the available options for bringing up the task switcher. I have to be careful not to forget about apps I've got open now, as having a few open at a time kills the speed and smoothness of the UI. Still, being able to leave my GPS apps open tracking runs or doing navigation, while answering texts or emails makes it worthwhile. I hate having to wait for the GPS apps to re-sync to satellite and resume tracking just because someone sent me a text.

I agree with Carlton on the idea that the less I do to the core of the OS (SBSettings, Winterboard, etc) the better. These things don't have a ton of excess processing power and throwing too much at it ends up dragging down the slick, smooth interface that makes iPhone ownership so pleasant. Knock on wood, but so far I haven't had a single signal drop since I ditched the hacked carrier settings and Cydia. MyWi with USB tethering has worked perfectly for me and does seem to be a bit faster and more stable than the WiFi setup.

About your issue with having to restore after crashing, I've seen that happen to one other person, and he had an iPhone 3GS, and also didn't jailbreak until version 3.1.2. The recommended way to upgrade for those of us who were jailbroken before 3.1.2 was to download a pre-jailbroken firmware and update using that. For a while, the 3.1.2 jailbreak was kind of sketchy, but I wonder if that is why you both had problems. Either way, I have never had a problem with my jailbreaks, and I've had five different iPhones (between my wife and I), all jailbroken and no problems. So, don't give up! I would say, use Rock (avoid Cydia), and install programs one at a time, a few days to a week apart each. This way, you can pinpoint if a particular app is causing you problems. And as Erik commented, the carrier profile hack to enable tethering is NOT a good idea, simply because it overwrites your carrier settings! I used that method when it first became available on 3.0, and it made it so that I couldn't use visual voicemail or MMS. Now I'm on MyWi (I shelled out the $10) and it works great. It is simply amazing. I'm actually using it right now for my internet connection, meanwhile, I have files downloading on BitTorrent in the background! I've even used it to play Quake Live, without a bad ping time at all. And Erik, while the WiFi method does work great, I would definitely recommend that you try the USB method. It's more secure, charges your iPhone at the same time, and taxes your iPhone less (which means less heat, etc). But if you have a reason to use WiFi (multiple devices, etc) by all means do so, but don't dismiss the USB method out of hand. I've noticed a slightly better connection with USB as well.

I could never go back to a plain Jane iPhone again, after experiencing the joys of jailbreaking. Now, some of the best apps that I think you missed, and what really make it worth it for me, are the following:

Kirkae and/or ProSwitcher- these apps provide a task switcher which lets you easily switch between your running applications. ProSwitcher lets you swipe between screenshots of your running applications, Palm Pre-style.

Tlert or QuickReply- once you use either one of these, you'll be hooked forever. They really should be a part of the iPhone OS. What they do is allow you to respond to a text message, no matter what you are doing on your iPhone, without quitting the app you are in and going to the messenger/sms app. With QuickReply, when the usual text message alert pops up, you'll see an extra button that says 'Reply'. Hitting that brings up a keyboard, allowing you to type out a reply and hit send, while the app you are working with patiently sits in the background until you return. These apps even work at the lockscreen, allowing you to reply to a message without even unlocking your phone!

Elert- This app pops up a preview of your received emails, so that you know whether or not you need to reply ASAP or can ignore safely until you have the time. I seem to have trouble on it with my phone, though, so YMMV.

Music Controls- If you, like me, love Pandora, then you'll love this app. Simply, it lets you control Pandora with the same controls that you use to control the iPod app. When combined with Backgrounder, this means that you can pause or skip forward to the next track while doing something else on you iPhone. Works from the lockscreen as well.

dTunes and Safari Download plug-in- Not essential, but still a great app. It is a replacement for the iPod, basically it lets you download and play MP3s. This is quite handy (especially in conjunction with Shazam) when you are out and about and hear or think of a song, but just don't want to wait until you get to a computer to listen to it. dTunes also installs the Safari Download plug-in which is what enables you to save MP3s from the internet.

WinterBoard- This was somewhat glossed over. Customizing your phone is great, especially when non-jailbreakers see it and can't understand how you have a custom background, or neat app icons. There is even a theme that makes your phone look just like an HTC Hero Android phone! Even without themes, the ability to add different SMS tones is worth installing WinterBoard alone. There are literally hundreds of different customizations that you can perform with WinterBoard.

FontSwap- Ever get bored looking at the same, Apple-controlled font? Well, with FontSwap, you can download and customize the fonts on your iPhone to no end! You can even create your own fonts to use.

SBSettings- This was of course already touched on, but there are a few more toggles that I think deserve mention as well, and these are: Rotation Inhibitor, which is great when you are using your iPhone in bed and are tired of the screen rotating when you don't want it to; Safari DL, which lets you turn on or off the Safari Download plug-in, and the Vibration toggle.

Because I'm a glutton for punishment, I went ahead and reinstalled Blackra!n, but this time I skipped Cydia and I'm using Rock for package management. I also did *not* install the peacefulinsanity carrier settings.

At the moment, I'm using a trial of a program called MyWi that can be purchased through Rock for $9.99. What it does is create a local WiFi hotspot through your phone and your laptop or whatever can connect to it just as you would any WiFi router. I think it also enables Bluetooth and USB tethering, but I haven't bothered to find out because the WiFi hotspot is working so well. Assuming that I don't end up having issues with the signal drops (which most people attribute to a combo of Snow and peacefulinsanity carrier settings), then I'm going to pony up the $9.99, as it's well worth it. I'll keep you posted.

The is a Cydia app called GV Mobile. It was available in the Apple Apps store for several months, then pulled when Apple decided to go Anti-Google Voice. The developer then released it through Cydia. I added it to my list above.

By the way, I can't remember if we've ever formally met or not. I was on UofL's FSAE team in either 00-01 or 01-02 off and on, and hung out with the Formula and Baja guys in the shop quite a bit those years. You had graduated by then, but I seem to remember you being around a bit here and there. I graduated from Speed with my BSME in '03.

I'm not turning back yet, but I'm keeping an eye on it.