Aside for support for Mac OS 10.5.5 and above other features would include -
Sync your iTunes playlists, calendars, contacts, notes and tasks
Add/Remove applications
Update your device when new software becomes available
Backup and restore your device data with such features like automatically scheduled backups and optional encryption
Manage multiple devices
This has been a while coming and it’s still a little wait away. You can register for updates here so that RIM can inform you of the software’s official launch.