gpl violation?

[rck at sonnenkinder.org]

Hi,
 
I don't know if a company is violating the gpl or not.

They use gpl covered code (linux, busybox,...) for their
firmware and the have released a tarball for an old version of this
firmware. Let' say version 0.1 and a 0.1.tar.gz.

Now they have released several version of their firmware as
binary-only and as far as I have checked, the only modifications
since 0.1 deal with their own proprietary code. So no changes in the
gpl-covered stuff.

Is this a gpl-violation or not? Are they forced to release the
source of the other >0.1 versions? 

The faq on gpl-violations.org says:
"For each and every version of the executable program, you have to
release the precisely corresponding version of the complete
corresponding source code."

I interpret "for each and every version" in that way, that this
company has to release additional source code versions. One for each
release of their firmware, i.e., if they release binonly-0.2.bin,
they have to provide a 0.2.tar.gz.
On the other hand I do not fully understand the "corresponding
version" part. As the gpl-covered code in the later versions is the
same as in version 0.1 (which is published), is it enough if the
company only publishes version 0.1 of the code? Is this the
"corresponding version"?

Regards, rck