Bing today announced that they will now drop the beta tag from the Bing crawler known as msnbot and change its name to bingbot.
Microsoft Bing proposes to effect this change from October 1st, 2010. Bing will drop the beta designation from the Bing search crawler and change the name of the crawler to reflect Microsoft’s new brand for search. Instead of the old msnbot 2.0b showing up in your server logs, the updated user agent will be:
Mozilla/5.0 (compatible; bingbot/2.0 +http://www.bing.com/bingbot.htm)
The HTTP header From field will also change as shown below:
bingbot will still honor robots.txt directives written for msnbot, so no change is required to your robots.txt file(s), says this blog post at Bing.