Notifications

One aspect that was not in the SDK was the ability to have an IM message come up when the application is not running. 

Apple says the wrong method is to run in background because battery drains and because it takes up CPU resources. 

Apple Push Notification Service establish one persistent service

Badges

Custom Alert Sound (the AOL sound)

Custom textual alerts (like SMS) with buttons to automatically launch applications

The Service will be available in September but Apple will start seeding developers.