At the W3C we have developed a protocol called WebID which allows RESTful authentication using only well established standards. It is designed to be RESTful, and can only become more so. But it would be very good to have some feedback from the community here to help us improve the language where possible.
The editors draft is here, and is evolving cosntantly
We get people from many different backgrounds working together and when one is in the middle of editing something it is difficult to see it a fresh. Keen fresh eyes are welcome. :-)
Social Web Architect