Apple recently began high volume testing of the push notification system with a special pre-release version of the Associated Press news app that is finely tuned for the upcoming iPhone 3.0 OS.

Applications that will be utilizing the push notification system will ask for permission first, like apps that use location will ask the user first before using the GPS feature. Once the app is authorized for push notifications, there will be a setting for Notifications in the Settings of the phone. From there, the user can finely tune the push notifications to their liking with the three options: Sounds, Alerts, or Badges.

Alerts will be similar to the SMS pop up, badges will just place a number in the top right corner of an app's icon, and sounds will accompany these if the user pleases. 

Overall, seems the push notification system will be very polished and well worth the wait in the 3.0 OS coming this summer.

via MacRumors