Last week, Microsoft announced on the Bing blog that Bing would be incorporating Twitter search results:
Today at Web 2.0 we announced that working with those clever birds over at Twitter, we now have access to the entire public Twitter feed and have a beta of Bing Twitter search for you to play with (in the US, for now). Try it out. The Bing and Twitter teams want to know what you think.
Bing also announced that bringing tweets to Bing will respect the existing privacy settings of Twitter users:
By the way, you won’t see any of your tweets if you protected or deleted them, and tweets don’t last more than 7 days in our index