uPnP connectivity would be interesting depending on M's strategy. Connecting to Sooloos is a given but the ability to also connect to other standard media servers would make the market quite huge for them without necessarily damaging Sooloos.
Leave Sooloos for the serious SQ setups and have Sooloos/uPnP for the C12 so it could work and connect pretty much to anything....wherever you put it.

Think of the territory grab M could make with this...it's would be worth a thought....

For the Sooloos application in a C12 I think it could do worse than to replicate the type of screen you get on a SB Touch. This could be mounted on the front or top of whatever shape they ended up with.

Wired and wi-fi.

Internet radio.

Not too fussed personally about the video side of things, but, understand that it would make sense to go BR and HDMI provided it wasn't too expensive for those that didn't want to the picture outputs. Not sure if BR licencing would be the expensive bit.

cheers

Rgds,
Nick