Bing announced they are testing adding Twitter posts directly in their search results. Both Google and Yahoo already do this, and now Bing is going this route. Bing did offer tweet answers in the web results and they do offer bing.com/twitter but this is new.
I personally do not see the test, so here are screen shots from the Bing blog:
Yes, a section for "social results" for hot queries.
For navigational queries, Bing will show you the most popular shared tweets from that site.
Forum discussion at WebmasterWorld.