If you're currently making use of the popular Launcher Pro, you'll want to hit up the Android Market and check for updates. Version 0.8.3 is now available for download and while it's not a huge release, it does add some fancy new transitions. You'll be able to find the transitions through the settings:
- (Menu > Preferences > Homescreen Settings > Transition Effect)
If you've not grabbed the update already, download link is after the break. Thanks, El Jefe!