incrediBILL - 1:02 pm on Jun 29, 2010 (gmt 0)
Per the Bing blog [bing.com]:
On October 1st, 2010, we will drop the beta designation from the Bing 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:
So anyone herding msnbot using .htaccess or other means will need to start adjusting your software accordingly.
However, don't worry about your robots.txt file however, because they plan to retain backwards compatibility.
We want webmasters to know that bingbot will still honor robots.txt directives written for msnbot, so no change is required to your robots.txt file(s).
There was no official mention about whether their rDNS used for bot validation would change so I suspect it will still retain the following format: