Not really comparing like for like though, given with an iPhone you can have any wallpaper you like behind the icons. Don't get me wrong - I like the WP7 approach. But out of all the colours I only ever use two or three. Some are too lurid, some too girly, and some too...well, brown. And who wants a brown phone?
Personally, I'd love a few more colours. Grey (as seen on the HTC Radar), black, white and a couple of darker ones (the maroon colour in particular I like). Interesting that some of the colours coming up on the WP7 stats are labelled "Mango Beta". That does make them sound more official, or at least more like they're supposed to be there rather than registry hacks. Maybe MS have some test colours out on test handsets?