"If I took a picture from Wikipedia and
incorporated it into one page on an
existing website, what would I have to release under the GFDL for that
inclusion not to violate Wikipedia's license? Would I need to release that
page, my entire website, or neither (just the picture) under GNU FDL?"
I'll echo the "I don't know"s, and add a complication: pictures and
text are a bit different. Almost all the text in Wikipedia was made
collaboratively, and is therefore unquestionably FDL. But many of the
pictures are either public domain or used under "fair use", so using
them in another work would have no affect at all on that work.
--
Lee Daniel Crocker <lee(a)piclab.com> <http://www.piclab.com/lee/>
"All inventions or works of authorship original to me, herein and past,
are placed irrevocably in the public domain, and may be used or modified
for any purpose, without permission, attribution, or notification."--LDC