The question is what we are concerned about: being sued, or about being above board with what we use and properly redistributable?
Certainly, in most cases, Wikipedia is safe from being sued.
Have you noticed, by the way, that the current trend on image copyright is NOT 'assume good faith' on Wikipedia? We no longer assume that reading a statement and clicking yes to agree is sufficient -- we require people to justify.
-Matt (User:Morven)