How do you use push notification on your iPhone? Apple released the push notification service as part of iPhone 3.0 and since then iPhone and iPod touch (and now iPad) users have been able to get everything from social network updates (Instant Messages (IM), Twitter tweets, Facebook statues) to game challenges to deal notices to.. just about anything you can imagine.

Some users are forgoing SMS for push notifications to save on texting costs. Others like RSS feeds, or breaking news on certain topics pushed right to them. There are even apps who only provide push notifications for other apps!

iPhone OS 4 will add local notifications to the mix, so App Store alarms, for example, could even be set to wake you up in the morning. (Would that iPhone OS 4 also fixed those push notifications pop-ups that obliterate everything that came before and provide no way -- webOS or Android style -- to manage them. Bitter much?).

So we're curious, which apps are you using push notification for right now, and how are you using it?