Google Book Search Within SERPs

A new way to vertical creep into Google SERPs is through Google Print, oh I mean Google Book Search.

I was reading this thread on SEO Inc. Being Penalized and someone linked to a Google search on search engine marketing firm to show that they were listed (I don't see them). But that isn't the case, if you go to the bottom of those results, you will notice a link that reads;

Try searching for search engine marketing firm on Google Book Search

And guess which book ranks number one? Cat Seda's! Congrats!

Forum discussion at Search Engine Watch Forums.