I'm taking the first steps down the road of integrating BizTalk and DAX. By many accounts, it's not the straightest road, but I'm up for the challenge :) I'll include any learnings on this as I go. In the mean time, here is where I have started on this road:
Microsoft Dynamics AX 2009 AIF BizTalk Adapter Configuration White Paper
http://www.microsoft.com/downloads/details.aspx?familyid=EDC62433-5B21-4F74-B065-B075BA6DC86D&displaylang=en
Latest BizTalk HotRod issue
http://biztalkhotrod.com/Documents/Issue7_Q3_2009.pdf