Google released the Android Device Manager back in August, but only with a Web-based interface. It allows people to ring, lock, or wipe their device, but it was confusing as there was no app version, while Find My iPhone exists in iCloud and as a mobile app. That is now corrected.
Although people were confused by the lack of app support for this feature, theoretically it is more important to have a web interface. After all, if you lose your mobile device you will need a different way to find it, and that could be "just any old Web browser."
On the other hand, many people now have multiple devices, so they could always log on to their other Android device to track the missing one. For those (and we know some) who have one Android device and one iOS device ... you'll still need to rely on the Web for either Find My iPhone and Find My Android, er, Android Device Manager.