There is some early discussion over at WebmasterWorld that Microsoft Bing has updated their search index. Many webmasters are discussing changes in rankings in this and other forums (which are hard to link to).

Here is what WebmasterWorld moderator, martinibuster wrote:

For this site, I can tell you Bing sends up more traffic than Yahoo.

The last Bing update we reported was in late October.

Forum discussion at WebmasterWorld.