For the conspiracy theorists out there, this is a gold mine... Let's see... maybe Sony was so upset about their fortress of a system finally being hacked, that they secretly allowed (dare I say, encouraged?) the attack so they could publicly say, "See, you should have left it alone." Then they fix it with a mandatory update - perfect opportunity to patch up the exploits and prevent further homebrew development!
In all seriousness though, I would be suspicious about what else they are including in this mandatory update - it is the perfect opportunity to include some things that most users may prefer not to update otherwise.