The open social party is apparently the place to be. Even old Microsoft just announced LiveMesh).Now Yahoo, who's Flickr photo sharing site is the second most popular used API on the web, has rolled out a limited preview to the developer platform they announced in February called SearchMonkey.The limited developer preview was announced by Yahoo! CTO Ari Balogh at his keynote speech at the Web 2.0 Conference held last week in San Francisco. According to the keynote, SearchMonkey is just the beginning of a new directive called Yahoo!Open Strategy, or Y!OS.SearchMonkey is the tip of the iceberg; in the keynote Balogh said that eventually they will allow developers to write applications for all of Yahoo's services.Yahoo, who by their own account get 500 million unique visitors a month, insist they are not building yet another social network, but are instead "unlocking it". On their corporate blog, they say: "We are rewiring Yahoo!, building platforms that fundamentally change how Yahoo! works. We’re also opening up to developers to take advantage of the social aspects of our many favored destinations, creating what we call “vitality” — a lifeline into what’s happening with your social connections". With SearchMonkey, a user can see a "mash up of helpful data" along with their search results. Developers will be able to write applications that a user can download to modify their experience on the site, similar to the way Facebook allows members to download applications.For now, it looks like someone may have forgotten to register SearchMonkey.com (a visit to the site brings up a generic splash page) but like any good new venture, they are kicking things off by throwing a party at Yahoo Headquarters in Sunnyvale. Interested developers can apply for a developer preview with a brief statement of the application they'd like to write.