They didn't intentionally make it public. The videos and so on were leaks. The internet seems to have decided that Microsoft intentionally leaked this stuff to

They didn't intentionally make it public. The videos and so on were leaks. The internet seems to have decided that Microsoft intentionally leaked this stuff to disrupt the iPad launch, but I find that very unlikely considering that according to these and other stories, the project was already in severe danger of being killed by the time the videos came out. It's more likely someone on the team leaked them out of frustration with the impending cancellation - leaking something you're about to kill is not a PR win (as we've seen).