I'm not so sure. Raymond C. is probably in India and is certainly guessing. See the reader comments at the bottom of the above URL.
"AT&T said it does not manage or approve apps for the virtual store..."
My guess(tm) is that AT&T is trying to stall the introduction of Google Voice, which combines a mess of phone numbers to ring on one number. This is something that AT&T does not offer. If Google were to grab all the early adopters, AT&T would have a tough time convincing them to switch to the inevitable AT&T clone of Google Voice. Stifling innovation comes to mind here.