On my Macbook Air running OS X 10.8 Mountain Lion, when I click on the Time Machine backup menubar item, I see the option to browse other backup disks. That’s a pretty cool option, if I need to switch between different disks to backup my Mac; maybe to make a secondary backup for redundancy.
In Mavericks, the Time Machine menu bar icon doesn’t have this option any more, instead only showing Stop This Backup when backing up (or Back Up Now when it isn’t), Enter Time Machine, and Open Time Machine Preferences. If you’re wondering where the option to browse other backup disks has gone, you’re not alone.