The news of Yahoo's deal to use Microsoft's Bing for search at best has some standing vigil over BOSS and SearchMonkey (our profiles of the BOSS API and Yahoo Search API). At worst, many are already calling the services dead.
Last year, Yelp introduced its completely new Yelp Fusion API. Since its introduction, Yelp has dedicated most of its resources on the new API, and encouraged developers to migrate to Fusion. Over that time period, Yelp has added new features, fixed bugs, and now signals the end of the legacy API.