this article makes interesting reading:
http://www.insidemobileapps.com/2011/02/15/windows-paid-downloads/

The top paid app, Fruit Ninja, originally created by Halfbrick Studios, saw an estimated 49,800 U.S. downloads at its $3 price on the platform in January. When we covered Android’s platform a few weeks ago, the top app, Electronic Arts’ Need for Speed, was seeing an estimated U.S. 68,000 downloads per month at 99 cents.


and some early signs of the fruits of the MSFT/NOK relationship:
Mobile analytics firm Flurry is also finding that developers are starting to bite, with Windows Phone 7 project starts up 66 percent during the past week.