The iPhone Dev Team released redsn0w for iOS5 today. Apple also released the iOS5 GM to developers today. These tools are only for developers. I recommend you do not go update to this right now. Here are the reasons:
1) iOS5 GM will expire. It’s still for developers only. It may still be different than the final released version next week. Further, once jailbroken, you cannot use over the air update feature to update so you will have to restore to the new iOS5 final at some point.
2) Next Wednesday is not that long to wait for a final firmware.
3) As the dev team said, many jailbreak tweaks, the reasons you might want to jailbreak, are not yet ready to go and will not work on iOS5. There are many fixes developers have but have not yet released, because iOS5 is not out. Of these includes activator, which is used by a huge number of tweaks. Installing anything that relies on activator causes all apps to show up 1/4 sized on first reboot. There are other issues. Wait for official release by next week and expect a lot of core tweaks to be updated by then.
4) If you’re on 4.3.3 or any untethered jailbreak, the iOS5 jailbreak will be tethered (you will have to re-run redsn0w and do DFU mode every time you reboot your device). I do not expect an untether until after iPhone 4s is actually out and someone (Chronic dev?) releases a new jailbreak exploit. Note: Only old bootrom 3gs owners will be able to untether now.
5) If you’re on iPad2, you cannot use this to jailbreak iOS5. You must wait for the iphone 4s jailbreak.
6) From my personal experience and work I’m doing converting my own apps, I can tell you that iOS5 changed a lot internally so most tweaks will require an update to work.
7) Oh, and this may be a big one for some of you unlockers. But this version of redsn0w does not hactivate. This means you have to have working service on iOS5 from iTunes (or Gevey sim or such) before you jailbreak.
So again, I suggest you resist the urge, remember this is for developers only, and realize that waiting a week or 10 more days is going to make your iOS5 experience that much better when you do make the move.