On October 1, 2010, the Bing bot will not be in beta anymore. On this date, it is going to replace the current MSN Bot completely. The new User Agent line reads:
Mozilla/5.0 (compatible; bingbot/2.0 +http://www.bing.com/bingbot.htm)
The HTTP From header is going to change as well. Old:
Of course, the Bing bot will also apply robots.txt spider rules that you set up for msnbot. You can find more information about the Robots rules for Bing bot in the Bing Webmaster Blog.