To clarify the comment re: Bill Gates biggest regret, his biggest regret according to the referenced article was that Microsoft never shipped WinFS. He did not regret the product itself. It was unclear to me what the parent meant, as my first question was, "If he regretted it, did he allude to reasons why it's a bad idea?" But that question no longer makes sense when you realize that the Mr Gates ostensibly still believes in the idea.