From the Jason Conger blog, Microsoft releases a white paper talking about how they released Server 2008 Terminal Services internally before ever showing it to the outside world.

Microsoft maintains a development methodology commonly refereed to as "eat your own dog food" meaning that the products that Microsoft develops are first tested in its own corporate environment. One of the ways Microsoft "ate its own dog food" was to pilot Windows Server 2008 Terminal Services. The project was so successful that Microsoft IT went on to test the scalability and performance into the production environment (keep in mind that Microsoft has over 78,000 employees worldwide). The implementation of the TS Gateway feature was a major shift at Microsoft. Prior to TS Gateway, employees had to start a VPN prior to establishing a Terminal Services connection.

This implementation lead to a technical white paper called "How MSIT Uses Terminal Services as a Scalable Remote Access Solution - Deploying Windows Server 2008 Terminal Services at Microsoft". The white paper "...shares the experiences of the deployment team in the deployment of Windows Server 2008 Terminal Services at Microsoft. Also, because of the experience that the team gained during the deployment, this information should provide meaningful guidance to organizations that want to deploy Windows Server 2008 Terminal Services in both small and large terminal server environments." This really is a good architecture reference and an easy read with specific goals and solutions.

You can download this white paper for your own reference from Microsoft...