hi,
on the level of wiki-book projects, we have just launched the FLOSS Manuals bookstore...you can see it here: http://www.flossmanuals.net
and details on how to embed it here: http://www.flossmanuals.net/bookstore
Its an 'embeddable' bookstore -designed to fit on the sidebar of your site, and it advertises all books produced by the FLOSS Manuals community using the FM platform. We have some tools that enable print-on-demand print-ready PDF generation from the wiki. The format looks lovely...you can see an example of the PDF copy here: http://www.lulu.com/items/volume_64/3865000/3865224/9/print/g1g1_final.pdf
There is a photo of the books someone brought here: http://olpclearningclub.org/2008/10/ http://www.flickr.com/photos/curiouslee/2925910346/
adam