The latest tweets from some Twitter users are now showing up as snippets in Google's search results. They feature the user's Twitter picture, name, message, and when it was posted. Links in tweets also carry over to the SERPs.
For example, search for [kristi hines twitter] (who authored the popular column "Google Panda Update: Say Goodbye to Low-Quality Link Building" yesterday), you get this:
Seems to be a test, as Google hasn't made an official announcement. Also, this feature only seems like it only shows up if the user has tweeted recently, though the exact timeframe isn't clear yet before it reverts to the usual message that "x is on Twitter. Sign up for Twitter to follow..."
Soshable conducted a test and found tweets showing up within 2 seconds. Google is fast, but not that fast, so Soshable concluded that Google has tied their search results directly into the Twitter API.