It looks like the early reports that Sun’s cloud API would be compatible with AWS resulted from the reporters’ exuberance (or mere confusion.)
It’s actually nicer than Amazon’s.
It is based on the REST architectural style, with representations in JSON. In fact, I might start using it as the best embodiment of REST principles. You start with an HTTP GET of “/”. In this repsonse to this and every other request, it is the hyperlinks in the response that indicate what actions are allowed.