Facebook integration highly likely for iOS 6
There's plenty of speculation, ranging from improvements to the under utilised Game Center, a version of OS X Lion's AirDrop for easily sharing files, an Apple version of Google Maps, and improved iCloud support.
We'd also be amazed if Apple doesn't announce what it expects the industry to do about user tracking, as presumably it will take this opportunity to actually deprecate UDIDs.
There's another thing that's almost uncertain to happen - OS integration with Facebook.
Apple and Facebook almost got it together when Apple launched Ping (remember that), but for various reasons, they couldn't come to a deal and Apple went with Twitter integration into iOS instead.
Now, with Facebook shares in freefall, a post-Jobs Apple, and the obvious user experience enhancements a deal would bring, and everything points to iOS 6 enabling users to post their activity from apps and Game Center directly into Facebook.
Underlining this new-found chumminess were Tim Cook's comments at the recent D10 conference: "Facebook is a great company" ... "Stay tuned."