On itunes 10.5b3. I started a thread on this because I just awkwardly had to do so, after upgrading to beta 3, as a new iPhone like everyone said to do, then I couldn't restored from my icloud backup (as my last backup from beta3 was no longer showing up as a backup on iCloud), or on itunes. So I put my iPhone 4 into dfu mode, and it automatically brought me back to 4.3.3 on it's own. I know I've seen thread after thread asking if it can be done, and like always with beta releases, yes you can go back to the last public release. And just to throw it out there, I plan on just waiting for the public release of iOS5, as I'm not a dev. The final version of iOS5 is going to be a awesome step in the right direction as usual for Apple, and us, the users.