The Maemo-running N900 is the lucky phone that gets to try out the new OS. Since it's still pre-alpha, most of the features aren't implemented yet.
Maemo, which runs mostly on tablets, works like a charm for the N900, if MeeGo is anything like Maemo with hardware-support brought by Intel and a few other features from Moblin, we're in for a treat!
This is the first actual release of MeeGo; there was indeed
something published a while back, but since it didn't have a gui it doesn't really count. You can
view the screenshots or
download the source straight away.