The sixaxis is pretty much a terrible gimmick, as most reviewers have agreed. i think Heavenly Sword (5 hour God of War clone) was the only game to implement it well with the arrows.
Most of the hyped games (lair, motorstorm) were pretty much crap, and MGS4 isn’t looking too hot anymore.
Xbox Live does a lot more, i’ve heard you can’t even access the dashboard ingame on the ps3s xmb. that’s terrible.
It doesn’t seem like you guys really care about the games, as none of you have really mentioned them. So go for the PS3. PS3 users don’t seem to use or play games anyway. They seem more focused on justifying their purchase by rumor mongering the 360 online.
Also, the thing about the headset is a lie. I have a friend that’s used a 3rd party wireless headset for a month or two.