I have just be warned about a bug in BizTalk 2006 R2 and BizTalk 2009 in EDI:

http://www.axonolympus.nl/wd/pages/nl/BTS_EDI_BUG.php

If you are using EDI in BizTalk 2006 R2 or BizTalk 2009 you just have a couple of days to check if you are affected and to implement and test the fix.