Browsing other Time Machine disks!
I don't know if this is new to 10.5.2 or if it is because I needed the new Time Machine menu to notice it, but it is now possible to browse other Time Machine disks. I assume it works if you have done backups on multiples hard drives. It can be very useful to backup on different hard drives if you want to have a rotation and keep a hard drive out of your house/office. Here is where you can select which drive you want Time Machine to show:
1. Click on the Time Machine menu.
2. Hold down "Option", the "Enter Time Machine" should switch to "Browse Other Time Machine Disks".
3. You get a dialog box with a list of Time Machine hard drives hooked up to your Mac: