I have been working as a technical reviewer for a book that will be complete in April 2011 called BizTalk 2010 Line of Business Systems Integration from Packt Publishing. Pre-order is now available for the print form but some of the individual chapters are available now. Please check out this link for more information about the book: https://www.packtpub.com/microsoft-biztalk-2010-line-of-business-systems-integration/book.
It provides useful documentation of integration with Dynamics AX and CRM as well as various cloud-based services. The SAP chapters are very valuable and extend the currently available MSDN documentation for BizTalk integrations with SAP. This book would be an excellent supplement to your technical library. Thanks