That’s probably Win Phone 7’s biggest strength - you can program in pretty much any language, and use the dev tools you’re comfortable with.
If there’s one thing that Microsoft REALLY gets - it’s make it EASY and CHEAP (free, even) for devs to build products for your platform.
Or, they are great at making it seem easy and cheap, and then pile on the hidden costs (e.g. Visual Studio 2010 Pro is $799 or Sql server dev editions is free, but need an enterprise edition, that’s $15,000). And of course you have to buy the their OS to run it. Oracle runs their DB business in a similar way.