Here is the original source, with more information and less sensationalism. They aren't sure if any user information was downloaded, but are treating this as a full breach. To their credit, they at least hashed the passwords, and chose to inform their userbase rather than sit on it until they figured out if any user data was actually stolen or not.
No, they only informed those who actively frequent their sire, since all they did was post a warning at the top of the forums page. They took no steps beyond that. They didn't bother to send out a mass email to their registered users. I didn't learn about it until yesterday, 3 days after the breach, and that's only because I read it here on slashdot. If I hadn't read about it here, it would probably have been another 5 or 6 days before I learned about it, since that's about how often I frequent their site.