Early this week, Microsoft search engine Bing announced in advance its plan to change the name of its web crawler from Msnbot to Bingbot come October 1, 2010 to 'reflect' the company's new brand for search.

'Webmasters should know that bingbot will still honor robots.txt directives written for msnbot, so no change is required to your robots.txt file(s),' a Bing community member told COOLBUSTER.net.
Rick DeJarnette has a detailed explaination about this at the Bing blog:
In the <head> section of your site, find the following line:
And then replace it with:
You can also customize the content meta as follows:
Don't get too excited yet. Remember that you'll have to do this on or after October 1st just to play safe.
We will update this post everytime there's a pertinent announcement about Bingbot so be sure to come back here more often or bookmark this page for you to easily find this post later.
Rick DeJarnette has a detailed explaination about this at the Bing blog:
Instead of the old msnbot 2.0b showing up in your server logs, the updated user agent will be:If you already installed the meta tag for MSNBot on your site, there is no need to change anything. However, if you're the type of person who makes sure everything works perfectly, all you have to do is replace a single line of a meta tag.
Mozilla/5.0 (compatible; bingbot/2.0 +http://www.bing.com/bingbot.htm)
The HTTP header From field will also change as shown below:
From: msnbot(at)microsoft.com
will become
From: bingbot(at)microsoft.com
In the <head> section of your site, find the following line:
<meta content='index, follow, archive' name='msnbot'/>
And then replace it with:
<meta content='index, follow, archive' name='bingbot'/>
You can also customize the content meta as follows:
<meta content='index, follow, noarchive' name='bingbot'/>
Don't get too excited yet. Remember that you'll have to do this on or after October 1st just to play safe.
We will update this post everytime there's a pertinent announcement about Bingbot so be sure to come back here more often or bookmark this page for you to easily find this post later.