A little more done, well, another phase started anyway, on my XMOS challenge bot(s).
From the bottom up, an ATMega168 @ 8MHz (with lilypad bootloader), a 74LS14 to put the schmitt trigger thingies on the wheel encoders, and a SN754410 H-Bridge to actually run the motors. Top-right is the KA378R05 3A LDO regulator.
Now to see if it actually works.