Solutions that enable access to remote devices for security purposes are far from uncommon, but what is uncommon is having the functionality built right into the device, and especially with a solution that's simple to take advantage of. With a recent update to its Android Device Manager, Google has added the ability to remote lock, and remote erase - the perks here are obvious.
Should your Android smartphone or tablet be stolen, you'd have the option to log in and lock the device remotely, so that it simply cannot be accessed without a password. This can even be done if the device is locked with other security, such as a pin, and it can be locked-down well enough so that the thief couldn't even restore the device (easily, at least).
If sensitive data is on the device, you'd instead be able to erase it, which I'd imagine would simply restore the device to a fresh state. At that point the device could be used, but all of your important data would be gone.
I'm not sure how new this Android Device Manager is, because I've never dabbled with it before, but the "Ring" feature is one that stands out to me. Via the same interface, if you happen to lose your phone or tablet around the house, you can remotely cause it to ring. Bonus: It'll ring even if the volume is set to silent / off. Of course, if it were a phone, you'd be able to ring it from another phone, so this feature might be best-suited for tablets.
To enable these remote features, you must go to Android Device Manager online (found through the Play Store), and after sending a notification to your device, you can enable it. Geo-location seems to take place entirely by GPS, but as long as the device is online, it should be reachable through this interface.