After upgrading your iOS device to iOS 5 beta, the trick is to point Redsn0w 0.9.8b1 to iOS 5 beta 1 firmware file to jailbreak it.
MuscleNerd of the iPhone Dev Team has also confirmed this on Twitter:
Today’s 5.0b3 can be jailbroken with last month’s redsn0w http://is.gd/6eek4Y (point it at 5.0b1 IPSW..devs only please!)
After playing around on iOS 5 beta 3 while jailbroken, it has been discovered that AppStore applications do not work. They crash and refuse to open. It is an issue that has been reported by a few people, including myself.
According to hacker, Clayton Braasch it is due to a sandboxing issue:
To reiterate: there’s a sandbox issue causing App Store apps to crash after jailbreaking iOS 5 beta 3. Stay away if you’re not a developer.
It needs to be seen if this is due to some anti-jailbreaking measure introduced by Apple in the latest iOS 5 beta.
( Source : www.iphonehacks.com )