There is little you can do if your Mac is stolen other than make sure it's insured and take a note of the serial number for any claims.
According to the developers, there are 600,000 laptops stolen every year in the USA alone and about 97% of these are never recovered. However, Undercover offers an extra way to recover your Mac if the worst happens. It makes ingenious use of your Wifi enabling the developer security centre to locate your Mac within a range of 10-20 metres. It also makes ingenious use of your iSight - it takes pictures every 6 minutes of whoever is in front of your Mac and transmits them to the security center so your thief will be completely exposed!
Undercover doesn't stop there however. If for any reason your Mac can't be recovered, it reverts to "Plan B" which is basically to make your Mac unusable by completely dimming the screen. If the Mac is returned to a shop or Mac dealer for repair, Undercover even detects this and alerts the seller by both text and audio message that the Mac has been stolen.
There's no interface as such to speak-of. When you install it, you're given an Undercover ID that's unique for the Mac you've installed it on. When your Mac is online, Undercover routinely checks whether the Mac is reported as stolen. This is a bit concerning in terms of privacy but the developer's assure that Undercover will not send any identifying information from your Mac to it's server. Of course, the whole service comes at something of a cost although there are differing rates depending on whether you are s student, business user etc.
Undercover is the kind of security application that may be your only hope of ever recovering your Mac if it's stolen. If you don't want to rely on it, then make sure everything is backed up.