The third beta of iOS 6 has been released to developers running compatible iPhone, iPad, and iPod hardware. The new build is 10A5355d and contains many bug fixes and improvements over beta 2, pushing the newest version of iOS closer to it’s public debut later in the year.
For developers already running iOS 6 beta 2, they can download the beta 3 release quickly as an over-the-air delta update, found in Settings > General > Software Update. The new builds IPSW files are also hosted on Apple’s iOS Developer Center.
Some devices are seeing beta 3 marked as beta 2, despite already having beta 2 installed. This appears to be a typo and downloading the update installs the newest version anyway.
Apple has stated that iOS 6 is due for public release this fall. It’s looking increasingly likely iOS 6 will coincide with the launch of iPhone 5, and possibly even the much rumored iPad mini.