Regarding the ethernet's absense on the main unit: does the dock have any ethernet smarts or could a suitable dongle be created by a suitably determined individual?

Some of the ethernet components (the "magnetics", which I think means the isolating transformer and line driver) are in the dock. There are, in fact, a few dockless ethernet dongles here at Empeg Towers, but only because we thought we'd have to write all the networking code before the actual docks turned up. They aren't a very Good Thing, though, as the dock connector doesn't have positive locking -- it's only gravity that keeps Karma in the dock -- and so the dongles tend to fall off all the time.

Further this line of thought: will the charger on board the Karma function if supplied with only 500mA (think USB 2.0 charge/sync cable)?

I don't think it's smart enough to be told "here's some voltage, but you're only allowed 500mA of it", unfortunately. I agree that it would be a great feature, though.

Peter