I'm getting closer to having a working robot, although there has been a recent setback in that the new version of Ubuntu (9.04) doesn't seem to support the webcams which I'm using. This is odd, because they worked without a hitch in previous versions. A simple solution would be to downgrade the OS, although I'm reluctant to do that. I suspect that there has been some change in the kernel, perhaps related to gspca and V4L1 devices.
As a workaround I've continued development on Windows. This is ok, because the Windows version has not received too much attention and so was lagging behind in some features. My current strategy is to ensure that the robot's software works both on Windows and on Linux in order to maximise the possible range of use cases.
There's some extra work to be done on path integration, and no doubt there will be additional bugs to fix once I start testing on the robot in earnest (as opposed to simulation/unit testing). Both stereo cameras are working and calibrated, and are returning reasonable stereo features. The camera images seem to suffer from occasional glitches, and this might be something to do with their age (most of them were bought 4 years ago) or more likely it could be electrical interference with the USB cables from nearby pan and tilt servos. Either way, the glitches are not sufficiently serious to cause major concern at this point.