We've assumed that Twitter would be integrating Twitter Search (formerly Summize) into the main site for a while now. It seems that Twitter has accidentally confirmed this integration. A topic on Get Satisfaction, talking about new behavior for nudges, shows a screenshot of a newer version of the site, featuring Twitter Search. According to this shot, Twitter will implement keyword search via a box on the right side of the page. There is no word yet on when this update will go live.
Biz Stone, from Twitter, tells us that the screenshot comes from an admin account where they try different things out from time to time. Even though he doesn't give a timeframe for the update, Biz says that, "...we'll definitely be integrating the search.twitter.com goodness into Twitter proper soon."