Jim McBee is a great author and very knowledgeable when it comes to Exchange (and other things!)…I just heard that his latest book, Exchange 2003 24seven was finally published. I can tell you first-hand it’s packed full of great info – I was one of the technical editors for the project. It was a great book to work on…thanks, Jim, for letting me ride along as you put it together!
http://www.amazon.com/exec/obidos/tg/detail/-/0782142508/qid=1086028885/sr=8-12/ref=pd_ka_12/104-4023746-2671963?v=glance&s=books&n=507846