Over the last few months there has been a lot of noise and questions regarding ADFS support in SharePoint products and Technologies. First we were going to support it in Windows Server 2003 R2, then we pulled the support & now we will be supporting certian funcationality. Bascially it boils down to Office client integration. There is some funcationality that just wont work without work done in the client … primarily that is the stuff that is not supported now.
Read the full KB for a better explaination: