I needed a copy of the help files I could print out from my laptop which does not have BizTalk Server 2006 installed (I have it on a VPC but had trouble printing topic and all subtopics from there for some reason).
This CHM version just came out last week and is very good. The content has been greatly improved since the Beta 2 release and overall seems a massive improvement over the BTS 2004 documentation: http://blogs.msdn.com/luke/archive/2006/02/03/524534.aspx.