This is surprisingly fast because it has just been a week or so since Apple seeded iOS 4.3 Beta to developers, not today Apple has rolled out iOS 4.3 Beta 2, and yes, this build, 8F5153d, is meant for developers only meaning that those who are enrolled in the iPhone Developer Standard or Enterprise Program can get the iOS 4.3 Beta 2 by signing in to Apple Developer Connection.
iOS 4.3 Beta 1 brought many new features including new Multi-Touch gestures for iPad, HTTP Live Streaming statistics, better AirPlay capabilities and full screen iAD banners. Now iOS 4.3 Beta 2 can be downloaded from the iOS Developer Center.
Download iOS 4.3 Beta 2 for iPhone, iPad, iPod touch, AppleTV and SDK.