Later this month, Google will be releasing a new Android Device Manager to help you find your lost Android phone. Did it really take this long to implement? Apparently so.
Not only will you be able to locate your lost phone on a viewable map, the updated ADM will ring your device at maximum volume. And if it's gone for good then you can wipe your device remotely.
Devices running Android 2.2 or later will receive the update later this month. Google says a stand alone Android app will also be released for those with multiple Android devices. [Android]