I think you are on the right track. The GPL does not require you to release the source every time a keystroke is hit. If they are beta'ing the software solely for the feedback of the product, then so what.
If they enforced a waver making the "beta tester" part of the company, then there is nothing here (unless it stays beta forever). And if not, then we are once again complaining about a mistake on there part, and nothing more. These people had to "pay" to test out this product, it is not something you can just download online, or for that matter upload to everyone else.
As for Lindows, it is not something that I would want to use, or anyone else either.