Google maintain a controlling interest, but the founders themselves don't. I believe at IPO the founders controlled about 37.6% of the votes in Google and the board controlled 61.4%. So Google still got to direct Google (rather than their public investors), but the founders personally could be overrun by the board.
Facebook is one of the very few companies I can think of which is IPOing with a personal controlling interest from a founder.
I think a common tactic is to sell preferred non-voting stock during IPO, and retain voting stock for the founders. They get to keep control of the company, in exchange for standing last in line during a possible liquidation.