First of all, I find it odd that HBS even has a worldwide PR release of its' commencement schedule. That just goes to show you the stature of the school and the broad reaching access of its' Alumni. Source
There was another PR announcement yesterday as well about John Lithgow doing the Harvard undergraduate commencement. I'm not sure if the undergraduate and graduate commencement occur in the same area. What a contrast from say Wharton's commencement that will be having Allan Greenspan.