DevTeam hacker MuscleNerd has recently confirmed that the RedSn0w 0.9.8 b1 jailbreak works on iOS 5 Beta 2. All you have to do is to point it to a downloaded iOS 5 beta 1 firmware ipsw.
5.0b2 can be jailbroken w/redsn0w from 2 wks ago http://is.gd/6eek4Y (must point redsn0w at 5.0b1 IPSW)..devs ONLY please
MuscleNerd recently Tweeted that iOS 5 beta 1 jailbreak is already available. DevTeam released Redsn0w 0.9.8 b1.
For now the jailbreak is tethered (you have to run redsn0w each time you reboot) and available for Mac OS X only. It will not activate your device, so you need have registered UDID. iPhone 3GS users with 06.15 baseband: redsn0w will get you past the iTunes restore error. This redsn0w will probably work on future versions of iOS 5.