I think NDA-huntz has a place to send in an image file with your signature for that exact puropose....... ;)
I agree with the above sentiments, most likely your friend is someone who acquired it through a rapidshare link or torrent site and wanted to make you feel better about loading a beta OS on your phone.
FWIW, I attempted to load the latest beta for my phone and UMA died completely. So now I'm back to a hybrid of .18 and .10.