The mbed forum is quite active ... have you checked?
Even the most popular category on the mbed forum only has one message from today on it, so maybe not that active, at least compared to this forum!
The technology does look interesting though, and the programming looks pretty accessible - similar level of abstraction to Arduino.
Having said that I can't find a reason to buy myself a Due, so I don't know what I'd do with one if I got it!