Microsoft has released a significantly enhanced version of their Live Search API. Live Search API 2.0 offers increased flexibility in terms of API protocols (REST/XML and JSON are now offered, in addition to the original SOAP interface), new tools, sample code, and complete documentation.
Airbnb's CEO, Brian Chesky, hinted that Airbnb may soon open an API for third party integration. Chesky envisions the company shifting from a marketplace to a travel platform upon which third parties can plug into. While no specifics were given, Chesky suggested that lack of an API is a hole.