I believe there is a good chance that Apple will be improving the notification system in iOS since many months ago they hired the UI lead engineer from webOS that apparently came up with the notification system for Palm (now HP) webOS. I have used it a couple times and it was really elegant and not intrusive. So I will expect Apple to get something fresh for iOS 5. And who knows they may show some feature of iOS at tomorrow's announcement.

My guess is that they've hired a good designer who happened to work on the notifications feature, rather than hiring some sort of "notifications" specialist.

You hire someone with a view to them working with you for years and I don't think notifications is that big a deal that you'd bring in someone specific to do it.

At least fingers crossed that's it because it would be great to see something in iOS5.