In our recent APK/website teardown, we unearthed Android's upcoming remote device lock functionality through Google Play Services, and now it has quietly gone live in the Android Device Manager. Just head to the management interface and you'll have a new Lock button. Click it, and your lost device can be secured instantly.
The functionality is incredibly robust. Even if you have your device locked with a pattern, PIN, or other method, the Device Manger will instantly override it.