A friend and I were discussing this over the weekend, and we agreed with John Gruber's take:

[T]hat Zuckerberg was able to hold onto so much stock and an astounding majority of the voting rights is proof that his success is no fluke. The guy must be a badass at the negotiating table.

The kid is 27. For years he's sat across the table from some of the most powerful and successful potential investors in the world, and he has managed to preserve total control over his company. How could they all fail so consistently to gain control along with their ownership stakes, and how could he succeed so persistently in keeping both? Badass.