In addition to its core microblogging and social-networking features, Twitter has emerged as a repository of real-time testimonies on whatever is on people's minds, such as news stories of global importance, celebrity gossip and hot-button issues. As such, being able to capture, analyze and make sense of Twitter's stream of posts is seen as an important new area in the world of search engines.

"We're super happy with the Twitter partnership," said Qi Lu, president of Microsoft's Online Services Division, who was also on stage being interviewed by conference moderator Tim O'Reilly. Lu declined to disclose financial details of the deal. He also said he wasn't sure on its duration.

Neither Mehdi nor Lu said much about the Facebook arrangement, other than to indicate that it will be similar in nature to Twitter's but that it will be implemented at a later date.

It will be interesting to see what shape the Facebook agreement takes, considering that Facebook allows individual members to make only basic profile information available via search engine results. Facebook has indicated it may let members make their profiles open to anyone on the Web, including their status updates, but that hasn't happened yet.

Twitter, on the other hand, is a much more open service and most of its users make public their "tweets," messages that can't be longer than 140 characters.