Spotlight and Search: Apple has added search to its key applications including Mail, Calendar, iPod and Notes. Search for anything you like and find it fast. For the rest of your iPhone there's Spotlight, a fast and effective way to find anything on your device.
Push Notification: Some were hoping to see iPhone applications able to run behind the scenes, but Apple says that uses too much battery life. Push notification is the alternative, and will allow apps to send information to your device regularly. ESPN, for example, has an app that will send game updates video straight to your iPhone.
Calendar Formats: With iPhone 2.0 Apple added Microsoft Exchange support, and now they're opening up the iPhone's calendar to support CalDav and ICS formats. CalDav is the format for calendars used by Yahoo, Google, Oracle and Mac OSX Server and others. ICS is a subscription-based calendar that you can use to follow the schedules for your favorite teams and any other calendar that has a subscription option.