Yesterday I found an interesting piece written by Robert Hogg about SOA and ESB Architecture with BizTalk at Wrox. It is an Wrox Blox PDF containing 25 pages about SOA, BizTalk and ESB (Microsoft ESB Guidance). You can purchase it for $7 US, which is not much these days. It is good information and published last February. So if you have not read or heard about it yet, check it out.