A warning document in the beta files states that if you upgrade using this package then you cannot go back to an earlier version of the iPhone software.
|Pre-release software is Apple confidential information. Your unauthorized distribution|
of pre-release software or disclosure of information relating to pre-release software
(including the posting of screen shots) may subject you to both civil and criminal
liability and result in immediate termination of your iPhone Developer Program
Originally Posted by Solertia
I've been playing around with the beta and it's gonna be a great update
I dunno how well this leaked/hacked beta is gonna work, but if you have the opportunity to get it, do so, it's cool