iOS 5 Notification System Rumors
It's getting very close to the WWDC 2011 and it is believed by many that the iOS notification system gets a revamp. The former iOS notification system has been the target by many modules available on the Cydia App Store for jailbroken iPhones. One screenshot found by TechCrunch in particular seems to bring two different rumors together.
The notifications are displayed in the status bar which acts like a button to open a larger view to show all new (and maybe old) notifications. And since it is rumored that iOS 5 will offer a deep Twitter integration the "leaked" screenshot shows Twitter mentions, with a very slick status bar icon, too.
The single most interesting in my opinion is the stacking of notifications seen in the screenshot. E.g. that the notifications "You were mentioned by @iclouddev" and "You were mentioned by @mashable" would be aggregated and shown as a plain "2 mentions" in your status bar. This will make it easier to prevent user spam and still inform users about granular actions. (This was formerly available to app developers on Facebook, know as template bundles. Good times.)
P.S. Here is the best looking third party notification system I could find: MobileNotifier beta3, "Copious Corn Flakes"