Google is indexing Quora activity such as asking Questions, adding Answers, upvoting Answers, and submitting Posts. If you're interesting in learning more about optimizing your exposure on Quora, read this February 2010 post: Quora Optimization - Write Great Answers.
The list of sources included within Google's real time search is growing rapidly. News and blog links from Google, new and fresh Web pages indexed by Google, updates from FriendFeed, Jaiku, Identi.ca and TwitArmy were all part of Google's Real Time Search when it launched in December 2010. MySpace and Google Buzz posts were added in February, as well as Facebook Fan Page updates.