So I went and read up on it again. Apparently there's no clear consensus on the dynamic linking issue (still). Warning this post may get long. Here goes, so over at gnu.org in the FAQ it says this:

"However, in many cases you can distribute the GPL-covered software alongside your proprietary system. To do this validly, you must make sure that the free and nonfree programs communicate at arms length, that they are not combined in a way that would make them effectively a single program.

The difference between this and “incorporating” the GPL-covered software is partly a matter of substance and partly form. The substantive part is this: if the two programs are combined so that they become effectively two parts of one program, then you can't treat them as two separate programs. So the GPL has to cover the whole thing.

If the two programs remain well separated, like the compiler and the kernel, or like an editor and a shell, then you can treat them as two separate programs—but you have to do it properly."

But gnu.org also states:

"If a library is released under the GPL (not the LGPL), does that mean that any software which uses it has to be under the GPL or a GPL-compatible license?

Yes, because the program actually links to the library. As such, the terms of the GPL apply to the entire combination. The software modules that link with the library may be under various GPL compatible licenses, but the work as a whole must be licensed under the GPL."

But over at the Wikipedia article there's this:

"Some people believe that while static linking produces derivative works, it is not clear whether an executable that dynamically links to a GPL code should be considered a derivative work (see Weak copyleft). Linux author Linus Torvalds agrees that dynamic linking can create derived works but disagrees over the circumstances.

A Novell lawyer has written that dynamic linking not being derivative "makes sense" but is not "clear-cut", and that evidence for good-intentioned dynamic linking can be seen by the existence of proprietary Linux kernel drivers."

Now Lawrence Rosen, one-time Open Source Initiative general counsel argues this:

"The primary indication of whether a new program is a derivative work is whether the source code of the original program was used, modified, translated or otherwise changed in any way to create the new program. If not, then I would argue that it is not a derivative work."

But what there's more! The GPLv2 allows for a linking exception clause if the original developer(s) want to offer it.

"If you're using GPLv2, you can provide your own exception to the license's terms. The following license notice will do that. Again, you must replace all the text in brackets with text that is appropriate for your program. If not everybody can distribute source for the libraries you intend to link with, you should remove the text in braces; otherwise, just remove the braces themselves."

Much of it seems to come down to intent and good faith. While the pure application GPLv3 pretty much says no to linking, both dynamic and static, the legal definition of what constitutes a derivative work creates a grey area. It seems to come down to the intent of the developer(s) who license it as to whether it would be enforced that way but the dynamic linking issue is untested in court so no one seems to be sure if it's enforceable. Who knows? GNU, making simple things complicated since 1983.