Today Apple announced that they have licensed ActiveSync from Microsoft to enable full Exchange integration with the iPhone. The first thing you think of with ActiveSync is Push Email (that's when email is sent to your iPhone as soon as it is received, as opposed to on a schedule like every 15 minutes). ActiveSync includes that as well as:
- Wireless calendar syncing
- Wireless contact syncing
- Remote wipe of the device if it is lost
ActiveSync will be included in the iPhone 2.0 software, available sometime in late June.