I just wanted to express this loud and clearly:
At the Rockbox devcon back in June, we discussed this issue and we did deem the Rockbox license to be “GPL v2 or later”, so during this summer we have updated the Rockbox source code headers pretty much all over to reflect this fact. (Previously we had a bit of flux where the exact “v2” or “v2 or later” status wasn’t expressed.)
Of course we have not (and should not) change the headers for files we have imported into the project, and there are still pieces in Rockbox that are plain GPLv2 (without the “or later”) like a few snippets that origin from the Linux kernel.
We also did receive permission from Bernard Leach, the main ipodlinux kernel hacker, to put his code under the “v2 or later” label as well.