Microsoft is retiring its MSNBot1.1 and introducing its next bot: 2.0B. According to the Bing Community blog:
As MSNBot 2.0b enters full-scale production, the time has come to retire our previous generation bot, MSNBot 1.1. By the end of the first week in November, you will no longer see the following user agent in your referrer logs:
The only Bing user agent you will see in your logs from this point forward will be this, our new bot:
The Bing team promises the new bot will deliver a better and richer crawl accordingly.