Right now, there's a hot discussion about whether to ban the loading of non-GPL binary modules in the future. If this is agreed, then in the next 12 months, the kernel developers will notify by issuing a warning that they will ban a non-GPL modules and after that, they will put a patch which will ban the modules. This binary non-GPL modules will include the NVidia/ATI drivers along with other hardware that was only available as a binary modules (meaning not Open Source or partially Open Source).
You may also want to look for discussion about Driver Core for 2.6.19.
*** delete the code ***
Update (15 Dec 2006: 10:51): Linus has come out against the change, and, after some discussion, Greg Kroah-Hartman has withdrawn the patch. So it's likely that the kernel itself will receive non-GPL modules, but it only displays a warning just like what we had right now.