Wouldn't it be easier to build a standalone voip phone with a rasperry pi and avoid turning on a computer for skype altogether ? I'm not sure if you could do bidirectional video with the pi, but voice should be no problem.
OpenMAX code is quite fragile in my experience (from trying to use such libraries on Android phones) so I was wondering about writing a Python wrapper (based on the ctypes module) for the video encode/decode to make it easier to use. (Unless someone has done this already?)