Who would have thought this would ever happen? Microsoft, according to PocketGamer.biz, is throwing some substantial upfront money at developers of popular iPhone apps to port their products over to Windows Phone 7, which may be their last great hope of getting enough apps on the device to make it tempting. It doesn't seem to be going over all that well, since the word is that it's not really worth the money to go through the time and expenditure to port the C++ Objective-C apps over to Microsoft's standard formats of Silverlight or XNA Framework (C#).
One of their sources did say that there was the potential for Microsoft to alter their development frameworks to include C++Objective-C, but that remains to be seen. If if did happen, the time and labor factors would decline tremendously and the money would seem much better. But as it stands now, it's not going over too well in the development community.
Update: Sorry for the mixup. Both PocketGamer and 9to5 are citing the challenge of porting C++ games to C#; however, if the point is to move iPhone apps to WinPhone 7, as our commenters have rightly noted, then it's a migration from Objective-C instead.