New book in 2009 about Bayesian Networks: "Modeling and Reasoning with Bayesian Networks" by Prof. Adnan Darwiche .
Link download: http://gigapedia.com/items/346116/modeling-and-reasoning-with-bayesian-networks (make sure that you already log in into that site)
Link on Amazon website: http://www.amazon.com/Modeling-Reasoning-Bayesian-Networks-Professor/dp/0521884381/ref=sr_1_1?ie=UTF8&s=books&qid=1239663545&sr=8-1
I am trying to read some of chapters in this book to study about Bayesian Networks and find that it is written with a very comprehensive and straightforward fashion, especially help us easily deal with a lot of mathematical materials in Bayesian Networks with accompanying examples. In my opinion, it may be better than the typical book in Bayesian Networks, namely "Learning Bayesian Networks" by Richard E. Neapolitan, which is very tough to read and understand.