I jailbroke my iPhone 4 about a month ago and haven't had any problems. It was off for a day and when I turned it on, it's just stuck on the startup screen with the apple logo. Nothing's happened for 30 minutes. Is there a way to stop this other than a hard reset? I hope not because then I'll need to install 4.1 and won't be able to jailbreak it yet. Also losing some pics doesn't excite me too much, either.
You could try putting it into recovery mode with a program then kicking it out, sometimes this actually works
Are you using a Mac or PC? I'm not near my Mac right now but I can get you the program name when I get home in 2 hours or you might have to search for the pc version of the program