I have spoken to several people in the CRM community and according to what I have heard, although not directly from Microsoft, is that they will release an integration engine for integration between MS CRM 3 and Dynamics Nav. However, it is uncertain if it will only concern the new version of Dynamics Nav, soon to be released or will work also for the current version of Nav. This is good news since the connector I have worked with from the Danish company Tectura has left many question unanswered and lots to wish for.
I still havn't had time to test the BizTalk connector and I havn't talked to anyone who has. If you have, I would very much like to know your feelings about it.
CRM and SharePoint Consultant