"What is a module?"
It seems that Jeff's long section on "what is a module" misses a rather obvious point. As he quotes, the GPL defines source code as follow:
"For an executable work, complete source code means all the source code for all modules it contains,"
Well, it is completely obvious to me that a dynamically-linked library is not "contained" in the executable work. Hence the "source code" does not cover the dynamically-linked library source code.
In any event, if in fact the library did have to be licensed under the GPL, one could not link against libc, for example. Ahh, but someone will say, libc can be re-licensed under the GPL. But, AFAIK, this is never done, whether by Debian or others. The LGPL specifies a specific set of crieteria that must be followed to accomplish this relicensing, which nobody follows. And the re-licensing is a one-way street: once licensed under the GPL, libc would no longer be under the LGPL. Thus, to permit proprietary software on such a system (or, under the strict reading, to permit any non-GPL'd app to link against the library), one would need to distribute 2 copies of libc, and somehow be able to control which libc a program links to, depending on the program is licensed under the GPL. Nobody AFAIK does this.
Then someone will say, who cares, this is only a technical issue. It is possible to do this, it just takes some more work.
To this I say: it is also possible, though it takes some technical work, to distribute KDE/Qt under even the most restrictive GPL reading. One only has to not compile the KDE programs when doing the distribution -- just distribute the source code to the KDE programs (in which case Section 3 does not apply) and have the install program compile the KDE programs "on the fly" (in fact, one can make good arguments even under the strictest GPL reading that the distributor could go all the way to creating all the .o files for KDE, as these are not in any way linked to Qt, which then only have to be linked at install time). Yes, this is somewhat inconvenient, but not much more inconvenient than having two libc's and having each program link to the correct one. It is possible.
There are many more issues I could raise, and at other times have raised on the kde-licensing mailing lists. I will not rehash them here.
But one thing I can say is: it's pointless for non-lawyers to debate endlessly the meaning of the GPL. The fact that non-lawyers are doing the debating leads to one of the most common mis-interpretations of legal language, repeated by Jeff: he states that "to be licensed as a whole at no charge to all third parties under the terms of [the GPL]" means "under terms no more restrictive" than the GPL. This interpretation is totally implausible. Either the language means that the entire program (including all modules) must be licensed under the GPL -- which would pose huge problems for programs which are BSD or X licensed (and for this practical reason even the Debian folks don't seriously push this reading) -- or it means, as I have analyzed elsewhere, that only two requirements of the GPL apply to it: 1) that the source code be distributed, and 2) that the program be redistributable without charge.