Ian Graeme's new book "Business Rules Management and Service-Oriented Architecture" is a fairly technical look at business rules, the technology of a business rules management system and patterns of using them. The book gives a fairly quick overview of SOA and then introduces business rules, both as an approach and as a class of technology. He covers different execution styles, the features of a Business Rules Management System (I have my own list here) and compares three products (Blaze Advisor, JRules and Haley). For JRules and Blaze Advisor at least he is already out of date in the details but you still get a feel for the products and his method for evaluating tools is a useful read for anyone who likes to compare rules products with the traditional list of features.
Ian builds on many of the basic methodology steps outlined in previous rules books (like Barbara von Halle's) and then adds a really interesting section (about a third of the book) or patterns for requirements, elicitation, development, writing and organizing business rules. While some are fairly straightforward it is still a nice set and an interesting approach very suited to a more flexible methodology (like agile or similar).
I enjoyed the book and if you are looking for an up to date book on rules and SOA this should be on your list.
You can buy the book here.