Lucky me, I'm working with BizTalk Server on a major B2B project. There isn't too much information about BizTalk Server on the web compared to the amount of .NET information out there. So I collected what I could find and posted it as another overview (along with Scrum, XP, Lean Software Development, and .NET Test Driven Development). If you work with BizTalk Server, let me know what you think, what to add, etc.
Check out the BizTalk Overview.