Mashery (http://mashery.com/) has done this for Netflix, Rotten Tomatoes, and others. I think they're more about providing useful API access technologies than actually doing contract work to get things set up though.
(From their company page, http://mashery.com/company: "We help brands... manage (their) API Powered Platforms..."
And for high-level guidance, http://redmonk.com/, kind of a Gartner for platforms/developers.