The previous discussion I found on this topic only discussed the fact that Bing hosted copies of Wikipedia content.
What I did not see in the previous thread is that certain searches return a highlighted "reference articles on ....." link that searches returns only (Bing hosted) Wikipedia and Freebase results.
This is going to keep people on the Bing site for a huge category of searches.
For people who accuse Google of wanting to keep people on their own sites: so far, they have done nothing like this, and if that is your concern hope wish for Bing to fail.