iPhone 3.0 Beta 3 has been released, which is exclusively available for official developers and registered members. Registered developers can download it via http://developer.apple.com/iphone/. iPhone 3.0 is a real Beta intended for developers and testers, not for daily use on a primary phone. If you don’t need the beta, don’t install the beta
And yes if you are not Registered with the Apple than you can Download the iPhone 3.0 beta 3 here and And to jailbreak with QuickPWN 3.o Beta 3 follow this link
Very good info, thanks for the post.