Last April, a group of hackers broke into Sony's computer network and had a field day, stealing the personal data of 77 million PlayStation users and more than 50,000 songs*, including Michael Jackson's entire back catalog. The latter theft has just been confirmed by Sony, though they would not share any details about the material; various reports suggest that a number of unreleased songs, including duets with Freddie Mercury and will.i.am, were included. If that's true, then a boatload of brand-new Michael Jackson songs have been out in the world (or at least, in the computers of some very skilled hackers) for almost a year now without leaking. That is legitimately impressive.
* This post has been updated to clarify that 50,000 songs in total were stolen, and not 50,000 Michael Jackson songs. As our commenter pointed out, "no one has ever sung that many songs."