Google announced a pilot test which allows Google to provide Gmail results in normal search queries, including this example: "So if you’re planning a biking trip to Tahoe, you might see relevant emails from friends about the best bike trails, or great places to eat on the right hand side of the results page."
The Washington Post reported:
…the feature would cull information from users’ inboxes for relevant queries. A search for “my flights,” for example, would pull flight confirmation e-mails and match that information against Google’s existing flight tracking search feature. Searches related to other things, such as plans for the weekend, would also showcase e-mails related to that subject on the right-hand column of Google’s search results.