ooh I didn't know this.
How easy is it to setup time machine?
It's suprisingly easy. I did it last night on my new Mac Mini with Lion Server - all went smoothly.
1. Go to the Server application on your Mac Mini with Lion Server, and enable Time Machine.
It will ask you for the volume name you want to use for backups. I'd already created a partition on a firewire-connected HD for this.
It will turn on file sharing on your server automatically (if it's not already turned on). It then creates a folder on the volume called Backups, set up with the right permissions etc
2. Go into Time Machine preferences on one of your Macs, go into the 'Select Disk' thing, and you'll see something like 'Colin's Mac Mini - Backups'. Select it. It asks for a username & password. Type them in.
3. Repeat on your other Macs.