I just finished taking a skills assessment for BizTalk Server. Upon completion they provide useful links to information.

Official info from Microsoft:

What's New in BizTalk Server 2006
http://www.microsoft.com/biztalk/evaluation/whatsnew.mspx

BizTalk Server 2006 Application Deployment and Management (Downloadable white paper)
http://www.microsoft.com/biztalk/techinfo/whitepapers/bts2k6_appdepwp.mspx

BizTalk Server 2006 Business Activity Monitoring (Downloadable white paper)
http://www.microsoft.com/biztalk/techinfo/whitepapers/bts2k6_bamwp.mspx

BizTalk Server 2006 Runtime Improvements (Downloadable white paper)
http://www.microsoft.com/biztalk/techinfo/whitepapers/runtime.mspx

BizTalk Server 2006 Setup and Migration (Downloadable white paper)
http://www.microsoft.com/biztalk/techinfo/whitepapers/setupwp.mspx

Enjoy!

Ron