BookLamp.org

They say:

"BookLamp is a system for matching readers to books based on a full-text analysis of writing style, similar to how Pandora.com matches music lovers to new music. When you watch the video and play with the interface, examine the graphs, you'll begin to understand the depths of the data we're able to mine from a full text novel. You can see how the technology works, combining full-text analysis with self-learning systems to produce one of the most advanced book analysis systems in the world... we hope. :)"

There's a video here: http://beta.booklamp.org

Finally someone said something about it!
I am pretty amazed at the concept of it. Never would of guessed it.

Here's the video explaining how they do it:
http://video.google.com/videoplay?docid=-7242447315828172557