Sonu Arora, who I had the pleasure of meeting at TechEd this year, has just posted on her blog that her team has released an RC (Release Candidate) of the WCF Line of Business Adapter SDK to Microsoft Connect. In case you don't know, this is the framework upon which Microsoft is building their next generation adapters to systems such as Siebel, SAP, and Oracle Financials. It is based around extracting meta-data from the LOB application, and works entirely consistently with the WCF channel extensibility model.
If you read my blog and do BizTalk, and even more relevantly do BizTalk and SAP, Siebel, Oracle Financials or other LOB applications, then you'll want to look at this. Post R2 this would be the recommended route to take if you had a LOB application you needed to integrate with, rather than writing a Custom Adapter. You'd simply write an LOB Adapter in .NET using this SDK, and then implement with the WCF Adapter for BizTalk. The benefit there is that the work in the Adapter would be re-usable to other WCF .NET applications and not tied exclusively to the BizTalk object model.