Apparently its been around for a while but I only just thought checking to see if Microsoft had a Webmaster Tools site just the other day and it turns out they do. It's pretty much a copy of some of the things Google provides. If you've used the Google Webmaster Tools before, this will be a very familiar experience.
The authentication process is a little more involved and it checks to see if you are an authenticated user EVERY time you want to access a site statistics (not sure if Google does this everytime, it's a good idea). It means you can grant access to a remote user and then revoke it at a moments notice.
One tool stands out - the backlink checker shows the domains linking back to you and the sites rating in a scale of 1-5. The scale isn't very thorough and it's even more blunt than the 1-10 PR ranking method of Google's. But it is nice to see a tool that shows you each and ever page that is linking to you. I look forward to seeing Microsoft (and Google) adding some more innovative tools!
Visit the Microsoft Webmaster Tools Site.