I never would have suspected it was W. Mark Felt. Which I guess is what made the mystery endure for so long.
Fascinating. Learning about Watergate as a junior high school student in 1981 kindled my interest in politics and government.
By the way, for a flat-out fascinating recount of those days, and of journalism in general, read A Good Life, Ben Bradlee's memoir. Fantastic book.
More: O'Connor's Vanity Fair article is available online.