As a result of the 'Microtweet' deal, Bing gets access to all public tweets. We tested it, and messages appear in Bing search results roughly 30 seconds after they were posted to Twitter. If you then delete the message, they vanish from Bing just as a quickly.
On the face of it, Bing offers no more than Twitter's own real-time search engine. In fact, it only searches tweets from the previous seven days, whereas Twitter itself searches way back into history. But it does provide something unique.
When you punch in a search, not only do you see a list of the most recent tweets for that query, but there's also a list of the most frequently tweeted links about it. Furthermore, as most links posted to Twitter are shortened with services such as bit.ly or is.gd, Bing clearly displays the name of the site these shortened links are pointing you to.
To us this is where the real value lies for Bing, and it's not going unnoticed by Google. The Goog has also confirmed it will start integrating Twitter messages into its search results. It doesn't have a usable product yet, however, and when asked, a Google spokesperson told us it doesn't have a firm ETA, "but results should start to appear relatively soon."
You can try Bing's Twitter search service at bing.com/twitter.