Well it is not a point release so expect something as big or close to the changes from 1.x to 2.x. In that case it was the ability to run third party apps. This one should fix some of the deficiencies in the OS like push notifications, copy and paste, etc....
I would like to see a refresh of the notification system, and status messages on the lock screen, which I believe was hinted at a while back in a patent filing.
Would be nice just to hit the home button while the device is in standby and see a list of recent emails, SMSs, etc.
Ironically, that's the point of this event. They don't have anything ready, they just want to tell people what's coming. If they tell you now, their precious event will be pointless.