Replace my first paragraph with this:
The question before us then is this; can we state on our Wikibooks copyright policy page and on every edit page that by pressing save, the submitter is agreeing to grant Wikimedia a non-exclusive license to use their own unique and copyrightable work under both the GNU FDL /and/ any other copyleft license the Foundation may deem fit in the future (with a defintion of "copyleft" linked from that word)?
--mav