One account I read suggested Google made the leaps to constants early (and confused the other bidders with that move), but by the end were simply trading bids in the auction format's $100-million increments until the other side outbid them.

I can respect that; they still ultimately bid up to their reserve. Only earlier, when bidding was below what they expected the final price to be, they sent a geek-macho "we're still in the play-money range, fellas" signal.