Google's latest android app "Android Police", Your smartphone will find you.

Google has just released a new and very useful application to its Android Device Manager. Android Police is the Program which helps Android user to secure their lost or stolen device. Android Police has already looked at Android Device Manager v1.3.8, revealing that its only major new feature is the callback button.

When somebody turns on the screen of your phone, the lock screen will display a bright green button that can be used to automatically dial the number you've entered. This will make it a lot easier for a good Samaritan to reach you and coordinate the return of your hardware.

This feature is only work in smartphones -obviously- as tablets can't be used for calling purpose.
  
An image below shows the new security features