Ya never know...you would be surprised how many execs do lectures/guest presentations for college classes. Even at my school, not an Ivy or anything, we have had John Morgridge (former CEO of cisco) present for leadership classes , Leon Panetta (Chief of Staff under Clinton) holds a public policy class every quarter, etc... I can only imagine what schools such as Harvard can bring in as speakers/lecturers/professors

Often times powerful execs have connections to the school through alumni, children attending the school, other powerful friends, donors, etc... I myself have had the former CFO of 3Com as an accounting professor and a VP of Sun as a Intl Biz professor