Evolve or die.
The question was literally shouted at him, will you open your API the way Google does? The answer is no. And yet, by choosing "no," and letting a few thousand intelligent people hear that "no" loud and clear, Microsoft takes a huge gamble. Mix '06 is the company's best opportunity to make new friends and allies in a market where, Microsoft concedes, it has a lot of catching up to do. For the first time in years, other players are setting the rules, and Microsoft is choosing not to play by those rules. All of a sudden, Microsoft finds itself the outsider, the holdout, the would-be up-and-coming player, and Bill Gates finds himself playing the role of the conservative stalwart, resistant to change, impervious to the winds of history.
I don't know that it's a calculated risk so much as it is just obstinacy. It's a very good article, read it.