From the developer notes passed to us anonymously:
NEW: The minimum system version required for iOS 4.3 development is now Mac OS X v10.6.6.
FIXED: GameKit now reports an error when achievement or a leaderboard score is not actually submitted.
NEW: When in the preview mode of a UIDocumentInteractionController object, the Done button does nothing, leaving the application stranded in preview mode.
In the first beta, which was released just last week, developers were told that the SDK included support for new multigestures for the iPad. these included using four or five fingers to pinch to the home screen, swipe (up) to reveal the multitasking bar, or swipe (left or right) between apps.
A new line describing those gestures in the second beta release specifies, “This feature will not be enabled in iOS 4.3 for customers, but we are providing this preview to gather input on how these gestures work with your apps.”
Developers can find the new SDK at Apple’s Developer Connection. The rest of us can wait for the new iOS to actually be ready for release.