From the "Inside Office Online" Blog -

The online site for all things Office is now live.  this is where you can learn everything you would ever want to know about Office, and where you can even try out functionality in Office 2007.

According to the blog, the site is not beta, it's not RTM.. it's not GA.  This is the "RTW" (Release to Web) version. 

Here's the site:  http://office.microsoft.com/en-us/default.aspx

And here's the blog entry with more links and information: http://blogs.msdn.com/inside_office_online/archive/2006/11/01/we-ve-launched.aspx