Let's just be absolutely clear here that the content is under the GFDL, and anyone can use it commercially or in other ways if they follow the terms of the license. The only issues here are a) whether it is wise for the Wikimedia Foundation to do it at this point in time b) that the Wikimedia Foundation name was used inappropriately c) to what extent such uses should be documented on the Wikimedia projects.
Absolutely. And to my mind, none of these things are a big deal in this case. The name was used as attribution, though in some minor details perhaps in a fashion that might indicate endorsement of the commercial project, and the "documentation" of this seemed to be uncomfortable to at least Robert, who is of course a very important wikibooks admin.
There is always time to slow down and think. :)
--Jimbo