I'm confused reading zehjotkah's tweets.
The plan sounds so familiar with Maemo5, when originally we were hinted there would be two devices running M5. The 2nd device was said to be launched about half a year later than N900.

I am purely speculating.... seems like the plan is:
RM680: developer device, hw-wise not necessarily the same as N950 (no FM, maybe lesser CPU)
N950: Summer? Fall?
Second commercial device: Early 2012 depending on sale of N950?

Anyway, we'll know better the closer we get to the conference.