Microsoft Forefront Online Protection (FOPE formerly known as EHS and Frontbridge before that) uses a variety of technologies built on Microsoft platforms, as well as existing investments from aquired companies. At this time, Microsoft.com is in fact pointing to the FOPE service -- though there are other Microsoft properties that may or may not point directly to Edge servers at any given time -- as well as individuals whose email may bypass the service. I do recommend investigating the service based offering -- it does use some of the same technologies, but also additional technologies that are not available with the Exchange-based filter alone. In addition, there may be some significant cost & reliability benefits for hosting your MX records in the cloud. For more information, the FF team blog is available here:
http://blogs.technet.com/forefront/