Hey Lorna, I'm a little curious about how you feel about the "standard" these guys are trying to popularize when contrasted with your assertion above that "Response metadata is in the body, not header" is anti-REST. Granted, theirs is with respect specifically to JSON responses but it fits within the assertion I think...

http://labs.omniti.com/labs/jsend

I see the logic in both approaches... Would love your insights though.