Download Exchange 2010 Transport Server Role Architecture Diagrams…
This cool download contains architectural diagrams that illustrate the Microsoft Exchange Server 2010 Hub Transport server role and Hub Transport extensibility
http://www.microsoft.com/downloads/details.aspx?displaylang=en&FamilyID=6eb8c09a-6ea4-442a-9faa-de33265ceb84&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+MicrosoftDownloadCenter+%28Microsoft+Download+Center%29#tm