I received a notification from bot-trap that Microsoft is using a new crawling address for Bingbot:
A bad robot hit /bot-trap/index.php 2010-12-24 (Fri) 18:03:52
address is 188.8.131.52, hostname is msnbot-207-46-12-240.search.msn.com, agent is Mozilla/5.0 (compatible; bingbot/2.0; +Bing Webmaster Center)
184.108.40.206 is in the network range 220.127.116.11 - 18.104.22.168, which is 22.214.171.124/16 in CIDR notation.
If you use bot-trap, you'll want to add a line like this to your .htaccess file:
Allow from 207.46