, Bass wrote

I would like to see an open source, C#/Mono based mobile OS.

It's not really possible to make a really open-source mobile OS, because of legal constraints regarding the radio stack - specifically that base-band users (i.e. carriers) need to demonstrate that their users cannot be broadcasting traffic on someone else's part of the spectrum - which is pretty hard to do if you're going to be shipping the device with open-source drivers for a general purpose high-energy radio transmitter (which is the antenna of the phone).

That's why even Android - the open-sourcest of them all - still keeps the radio stack as Google-only closed source.