That hammer can result in more than just a slap on the wrist, however, with Sony outright saying that they will ban your console altogether from online play, along with blacklisting your IP. From the wording, it sounds like this would apply to all online use of the PS3, not just the Home service:
"Ultimately we know a user's details, we know machine details and we know where they live," said Edward ... “If you really, really misbehave you can have your console disconnected at a machine level, so you would actually have to move house and buy a new PS3 before you could get online again.”
Sounds a bit harsh, particularly when you are talking about permanently disabling a service that someone (in theory) paid for when they bought the console. Then again, Sony has never been shy about playing big brother. Taking it a bit out of context, it is somewhat like saying that a user banned from MySpace would be banned from the Internet altogether.
The PlayStation Home service, which they announced this year, is a social networking project mixed with a bit of MMO. It is schedule for a full release later this year.