BizTalk Server Operations Guide
Microsoft has just released the BizTalk Server 2006 and R2 Operations guide. The guide is available online from here : http://msdn2.microsoft.com/en-us/library/cc296643.aspx and is also available as PDF,CHM or DOCX. More info can be found at this location:
http://blogs.msdn.com/biztalk_server_team_blog/archive/2008/03/21/biztalk-server-operations-guide-is-pulished-on-msdn.aspx