The hData specs are well under their way through the bowels of HL7 – right now we are preparing them for official ballot submission within the ITS working group. Overall, the architecture has not changed that significantly since our earliest attempts, but we have added a number if useful features such as meta data, message API, and more. Since the demise of the RESTful profile at NHIN Direct, hData is the only project that I am aware of that tries to bring comprehensive RESTful architecture support to the Health IT industry.
I have uploaded the current versions, in case someone not on the ITS WG mailing list is interested.