This is a listing of their first party studios now
America
343 Industries
Connected Experiences
Good Science Studio
Kids and Lifestyle Entertainment
Microsoft Studios Los Angeles
Platform Next Studios
Playful Learning
Skybox Sports
Turn 10 Studios
Twisted Pixel Games
Europe
Lionhead Studios
Microsoft Studios London
Rare Ltd.
Soho Productions
Press Play
Canada
BigPark
Black Tusk Studios
Microsoft Studios Victoria
Microsoft Studios - Leap is another, but I don't know where to place it geographically, I think America though.
Microsoft is going to make a one stop shop console. It has to be everything to everyone and to do that, it has to be 'future-proofed' with technology. As they did with Bioware and Mass Effect and Gears with Epic, they are going to have similar agreements with 3rd parties. Remember Ryse from Crytek? That being one. Who is going to go out initially and drop money on this? The core gamer? We are going to buy it, stunt and show off in front of our friends, then they will want to get it. Someone has to be the guinea pig, the person that lives on the bleeding edge of technology, that is where we gamers come in. How does this happen, by playing new experiences. That stuff will Microsoft and Samsung is a great start.