HTC and Samsung are both building Windows Phone. It's not exclusive to Nokia.
For one thing, it's pretty clear that the initial batch of WP7 phones were more or less half-assed efforts - no distinguishing characteristics or designs, nor features either.
And, as the Nokia+MS partnership grows closer, and you start seeing some very tight software-hardware integration (a la Apple), HTC and Samsung aren't likely to stick around and play second-fiddle.
Why would they throw their weight behind the WP7 platform if the "officially blessed" version is always more tightly integrated with a better experience?
As long as qualifying as a WP7 integrator reduces the extor^H^H^H^H^Hlicensing fees for their Android phones.
ba dom dom tshh