Microsoft have just released the Microsoft BizTalk® Server 2006 adapter for Microsoft Dynamics® CRM 4.0, the adapter has the same functionality as the 3.0 adapter plus :-
• Support for both 32-bit and 64-bit deployments of Microsoft Dynamics CRM 4.0
• Support for form-based authentication
• Support the joy that is multi-tenancy
Best of all the adapter is free.