Being the paranoid person that I am, it occurred to me that it would be a good idea to back up Address Book and iCal before all of the syncing madness begins between Macs, MobileMe, "the cloud", and iPhone/iPod touch. Here's how to do it (Mac OS X 10.5 Leopard only):
Backing up Address Book
- Launch Address Book
- Select File > Export > Address Book Archive
- Find a location to save the Address Book archive, then click the Save button.
- Launch iCal
- Select File > Backup iCal
- Find a location to save the iCal backup, then click the Save button.
- Just sync it