A short book written by Beth Gold-Bernstein and Gary So, it covers the basic concepts, technologies and approaches of integration in the context of SOA. It has some good thoughts on how to build a business case for integration projects and infrastructure, some nice (if short) case studies, an outline of common scenarios and technologies and a quickie chapter on best practices. It's a fast read and gives a nice overview. Despite recommending not one but two or more competency centers (oh no, not another competency center) I found the book helpful and informative.
As you might expect from me, my only criticism was that there was too little on how to manage business rules in this context. Business rules come up but are not really discussed in enough detail. Not only do I think business rules have a role to play in integration and in SOA more generally, I think many of the scenarios where integration is useful are those in which the purpose of integration is to enable a decision. Business rules as a way to automate these decisions with agility is a key concept (though arguably one for another book).