Bing now has a new crawler. The new Bing crawler user agent string listed as:
msnbot/2.0b (+http://search.msn.com/msnbot.htm).
Note that the bot’s name for Bing didn’t change. You’ll also see the previous version of the bot as well:
msnbot/1.1 (+http://search.msn.com/msnbot.htm)
— which is still in use, as of today, as Bing’s primary user agent.