However, to get started, I have been working with Benjy (http://santoshbenjamin.wordpress.com/) lately and he sent me a link to a useful article so I thought I'd post it here. The reason I'm posting it is that one of the items that is detailed in here, multi-part message types in BizTalk, is going to be the subject of my next post.
The article is here http://msdn.microsoft.com/en-us/magazine/cc163423.aspx Enjoy.