A very notable advance in social search pretty much flew completely under the radar last week.
Social powerhouse Digg announced several important enhancements to their API which will make it easier for developers to build applications using Digg data. Much of the data and analytics surrounding Digg content will be enhanced on this revision of the API.
Digg has made available a search endpoint which provides developers the ability to find specific content on Digg. Developers will also be able to use some advanced shortcuts, common search tricks, and search by source (domain). More information is available on the Search API documentation.
A series of related stories endpointss has also been added. Developers will be able to build application which leverage Digg's related stories capabilities to, for example, find stories similar diggers have dugg. Another example might be returning stories with similar keywords. Digg most notably in my opinion has included an endpoint for favorites on Digg, which is a great way to determine which stories people find exceptional in some manner.
Finally, Digg has also made a subtle change to its API license, removing most of the commercial limitations which should give developers more control over the applications they create using the Digg API, with full ownership, i.e. no fees - hooray!