This is exactly what should have been done from the beginning. :clap:
It's good enough to prevent mass pirating of the music (or face consequences). But, it still allows for completely DRM free copying to your player of choice (As long as the player supports AAC I'm assuming). And, if you want to send it to a friend or 2.. there's not really any harm in doing so.
It's my bet that there will be a tool available within a few weeks (if not days) that will happily strip out these particular atoms. In fact, AtomicParsley can probably even do it for you, if you know the specific raw atoms to look for.
However, I'm not in the least bit surprised that information is still in there, and in fact a number of people have been proposing for years that you could probably remove the DRM and simply stamp the files to help discourage widespread piracy almost as effectively.
There are those out there who are paranoid that iTunes is going to "phone home" and track whether or not the content in your library matches your own identity, but I've always been a firm believer in the grassroots community of hacker watchdogs out there that helps to ensure that no large company like Apple or Microsoft would ever dare even try such a thing, as the negative PR fallout would kill them as soon as the first hacker came along with a packet sniffer and an eager desire to get their fifteen minutes of fame.