The software for the basic inverse kinematics is going slowly, mostly because I'm reorganizing the code that I already used in all the other robots, with a goal of making a library of it. In the meantime, I had a little distraction: I added the buzzer to a DAC pin of the PyBoard, and it turns out it's fast enough to play WAV files! After some mucking around with the turret lines from Portal, I finally used bfxr to generate some simple bleeps and pews, and then avconv to concert them to 8bit, 11025 rate files.

A video showing that I have control over the servos and the speaker: