Hardly anything. There's a book specifically about the Boost Graph Library, but a) the library is about to be rewritten, with probably significant interface changes and b) unless you actually need the graph library, there's no point in this.
Second up is boost. It's a great library with lots of promise. I found the book Beyond the C++ Standard Library: An Introduction to Boost By Björn Karlsson which is great, but it doesn't cover so much about boost. There is a great deal yet that lies hidden, just waiting to be explored. So is there any other resources or books about boost?