With current voting/Experience system in place, I think it shouldn't be of any difficulty to set something like that up. For one, you might start at it by simply creating a new user with a name suggestive of a book you'd like others to comment on. I know this is a crazy idea, but at the least it _is_ one ;D.
Another approach would be to actually create a book review user (a dummy user who wouldn't care about loosing XP here and there) and write up nodes for each book. Than, a book's value could be estimated from corresponding node (where the book is discussed etc). Again, this is one of the works solutions ;D, yet it is one!
Finally, we might petition vroom
to set up a voting 'booth' for books. Hack, I (or any other monk who feels like it) could write a script to do that and post it on my vladb.perlmonk.org site. Or we could even have it go under book.perlmonk.org. ;-)
"There is no system but GNU, and Linux is one of its kernels." -- Confession of Faith