Are these games free to play with your pay-to-connect XBox Live subscription, or will you still have to buy the games to play them? I'm unfamiliar with XBox Live (don't own an XBox and wouldn't want to pay another $15/mo just to connect it to the internet). If the subscription is free and the games are for-ay, that's good. If the subscription is pay but the games are free or extremely cheap, thats fine. If you gotta pay $15/mo + $5-$10 per game, no thanks, it is just a phone for chrissake.
Still, at launch, Windows Phone 7 will have more games available than they made available under Games for Windows Live! in like 3 years, so at least they're trying this time.