Has anyone used this?
http://www.appbrain.com/app/wheres-m...heresmyandroid

From the description, it sounds pretty cool. If you happen to lose your phone in your house, if you use another phone you can send it a text message with a password and it'll turn the volume all the way up and start blasting, so you can find it. Even better, if you use a different password, it'll text you back it's coordinates and address. Handy for that embarrassing morning after the beer garden.

But is it a battery and resource hog? I'm assuming the app has to be running in the background for this to work.