I think people are losing sight of the context within which all this OS evolution is taking place.

The mobile [internet] device market is in its infancy. We're taking toddler steps right now. Hardware is evolving at one heckuva pace. Radical changes are afoot. This isn't like the progression of x86 hardware, where we could expect successive versions of linux (frex) to work on older hardware.

If Maemo6 doesn't support the N900, for whatever reason, there is nothing to prevent the OSS community from taking any modular compatible improvements and back-porting them to Maemo5.

It's far too early to be getting a bee in our bonnet