Having mentioned my GPL TV the other day I feel I should point out the quick response from Panasonic. They pointed me to a website where the GPL components of the software can be downloaded. Now granted it's just a bunch of tarballs so there is not a recipe for how to build a firmware image to verify the code is correct. However I'll download the files over the weekend and at least check the Linux tarball isn't a vanilla kernel - which would be very surprising.
GPL section 3 does specify:
"The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable."
But I don't know if they have violated that term yet until I look into the code. So in summary it's helpful they have considered how to make the code available even if they haven't followed the spirit of the GPL.