Android is a nice proof of concept, like shr, windoze, (& ubuntu, fedore etc.) and for that matter, meego on the N900.
All of these, despite the fantastic efforts and accomplishments by the devs who continue to work on these (props guys!) have one thing in common: Not "fully" usable (in the context of maemo) on the N900 thanks to specific closed components by Nokia.
All of them bring different and interesting capabilities and offer testament to the skills of the devs who port them and the combination of hardware on the n900 that makes this possible to have them installed as alternative OS's at the same time.

While eager to try Meego on the N900 (again), I will be more than happy to keep using it with maemo and see what the "real thing" is like when it's actually released on a commercially supported platform that will (hopefully) include better hardware specs designed to provide optimum functionality and usability, not wait for nirvana on a platform that is only being used as a reference device.....
After all, just because the shoe fits, doesn't mean it's fit for purpose. I can run ubuntu on a 386, but that doesn't make for an enjoyable experience.
just my 2 cents......