A couple of updates - the source code for the Augen Android tablets I wrote about still hasn't been released, but the vendor does seem to be doing their best. Their supplier seems to be refusing to hand over the source code (they were given a tarball that was supposed to be it, but in fact just turned out to be the various GPLed bits of Android) and they're obviously stuck between a rock and a hard place. The obvious observation is that they should have done due diligence before starting to ship these things, but given that they're out in the wild and they're trying to improve things it seems reasonable to carry on working to try to obtain the source rather than insisting that kmart stop selling them.
Fusion Garage, on the other hand, are still failing to provide source and seem entirely unconcerned about it - they've failed to respond to any of my emails since the first. Augen aren't providing source because they can't, while Fusion Garage aren't providing source because they won't. Irked by this, I've decided to try Don Marti's suggestion and file a case with US Customs. I'll admit that I have absolutely no idea how seriously these cases get taken, and so I've no great expectation of any sort of interesting outcome. But even so, if you're in the US and try to buy a Joojoo then there's a chance that it'll be seized by US customs on the way in.