NC and ND are clearly incompatible with GNU/FDL.
CC-BY-SA on the other
hand is incompatible on a technical level only. That is, the rules
specify that one cannot cross-license, but the spirit of both licenses
is equal. Allowing CC-BY-SA is only a small step from requiring
everything to be GNU/FDL. Allowing NC or ND is a much larger step, and
we could not reasonably consider an article as a whole to be GFDL if
there are such images in it.
Well, true (although GFDL has that annoying requirement to
print/include the license alongside the product, which is why I
despise it for images), but I guess that raises the more central
question of: what is the big deal about WP being GFDL? My
understanding is that GFDL was chosen as the time partly beause it was
the most well-known copyleft license suitable for text. If we had that
time again, would we still choose GFDL? How about CC-BY-SA? How about
CC-BY-NC? What is the killer argument that Wikipedia should be allowed
to be reused in a commercial setting? (I obviously don't consider the
DVD argument to be a killer argument.)
Brianna