The good news is that, if you restore your iPhone it is like new and you will be able to update in the future with no problems. But that is only if you don’t attempt to jailbreak your phone again. Anytime Apple comes up with a update, it screws with jailbroken and unlocked phones. You can get around this by – (1) never unlocking/jailbreaking and updating only what Apple gives you or (2) you can hold off on updating right away, keep abreast of what our unauthorized developers are doing and when they come up with an appropriate jailbreak for that update, follow their instructions. And by the way, if it ever comes down to it, chose Restore instead of Update in iTunes. For some reason it doesn’t brick the phone (but it also erases any jailbreak).