According to Kara Swisher at All Things D, Microsoft's Qi Lu will take the stage at at Web Summit 2.0 this afternoon at 11:30am and announce a new real-time search deal with Twitter and Facebook.
While Swisher and other blogs are saying that these rumors are confirmed, as of right now (1:43pm EST), they are not officially confirmed. But you know how it goes when you get the "no comment" comment. Swisher is rarely wrong, so it's very likely this rumor is true.
In September, Microsoft began testing social sharing features that would allow searchers to share results with Twitter and Facebook, among others. Additionally, Microsoft launched BingTweets.com in July, which is a mashup of Bing search with Twitter's API.
It's probably safe to assume that any real-time search deal with Twitter and Facebook would involve more than just utilizing APIs.