Um...you don't have to wait...it's already out there in the wild. If the OS suits you, by all means, be on your merry...

There's a lot that the N900 does that other phones, and phone operating systems, don't do as well or as elegantly, or at all. So, I've gone back to mine - because the N8, the E7 and the C3 Touch & Type failed to meet my needs.

Nor the Thunderbolt with Android.

There may be things WP7 will do that the N900/Maemo can't - and I'm sure you'll enlighten me.

But apart from not being able to set contact-specific ringtones (and I'd only done that for a few contacts on other phones), the N900 is doing all I need - and is capable of much more.

Maps? - My car has its own GPS navigation system, so not needed there. For walking around, the functionality that's there is just about enough.