Microsoft provides 5 tutorials for beginning BizTalkers. The tutorials contain detailed steps for implementing simple scenarios to give new users an experience of using a variety of BizTalk tools while creating compiled, testable solutions.
Microsoft page with the article from the .NET magazine about the Sharepoint adapter for BizTalk written by Nikander Bruggeman and Margriet Bruggeman.
Interesting article found by a colleague (Thanks Bas!) of the BIA with things to know about BizTalk 2004 and 2006. The article is written by Naveen Karamchetti.