Here is a website where folks can purchase printed books based on Wikipedia content:
Currently featured books include: Quantum Mechanicshttp://pediapress.com/showbook/dcchcaruqoqeqfro/, Big Science http://pediapress.com/showbook/pcfyakskyfnqnigc/, 3D Computer Graphics http://pediapress.com/showbook/uidrpqgpwhpwilvl/, and Econometrics http://pediapress.com/showbook/irbexhnsmymhjbxw/.
Note that on the info page they admit that they may not be in full compliance with the GNU FDL, and that it seems to be so new that there is no Wikipedia article about it.
Comments?
Karl