Google Calling: Inside Android, the gPhone SDK (O'ReillyNet)

"A (non-trivial) driver NEVER does everything itself. It includes headers from kernel, which
in turn include more headers, which ..., in addition to using declarations from GPL-ed code,
results also in inlining GPL-ed code."

Yes, but if those things are found to be functional rather than expressive (that is, they're
just what you need to do to interface with the system), then including them arguably doesn't
make the module either infringing or derivative. 

Again, not a slam dunk one way or the other.