We recently made a special version of the 1337pwn XBOX Live Friends List web application for devices running Google's Android. This isn't a simplified browser version. It's a full-on AJAX application based upon our popular iPhone web application.
While almost no one has these devices right now, we are working on a native XBOX Live Friends List for the Android platform. The release of that application is at least a few months off as we don't like releasing mobile applications not tested on real hardware.
You can check out the Android web application here:
http://1337pwn.com/androidxbl.php
UPDATE:
We now have a native version in the Android Market. Read more here.
don't pwn alone(tm)!