Today at the Web 2.0 Summit, Marissa Mayer announced Google's partnership with Twitter to bring the search engine real-time search results. Just hours before Google announced the partnership, Microsoft released their own Twitter search tool on Bing.
Instead of being simply a way to search tweets, Google is planning to improve their existing search results by incorporating real-time observations. Here is an example Marissa gave in the official blog post:
The next time you search for something that can be aided by a real-time observation, say, snow conditions at your favorite ski resort, you'll find tweets from other users who are there and sharing the latest and greatest information.
This new feature isn't available yet (whereas Bing made their Twitter search available immediately after their announcement). Google says it should be ready in "the coming months".