WP7 is kind of interesting. If you would have asked me ~5 months ago about WP7 i would have said it will fail horribly. Now they actually do seem to be getting some okish selection of hw out for the WP7 launch and Microsoft is finally tying some of it's other products to WP7.
It still seem quite USA centric and WM was never much of anything outside of North America... then that might only be good thing for them. Out of the Android, Symbian, Iphone, MeeGo bunch it's not the one i want, but i can see the appeal it might have for some.

I really am not sure how will MeeGo handset ux fight against Android that's growing by the day. If MeeGo can produce this brand image of family of products(netbooks, tablets, phones) where Android has failed that could be big advantage.
Qt is still probably the key and before that MeeGo needs to have lots of appeal to get that initial push. Just hopefully Symbian is also able to gather devs for the Qt side.