In the wake of recent developments in Sony's war on Geohot, the company has released an "Official Statement Regarding PS3 Circumvention Devices and Pirated Software," which reads, in part:
Consumers using circumvention devices or running unauthorized or pirated software will have access to the PlayStation Network and access to Qriocity services through PlayStation 3 system terminated permanently.

To avoid this, consumers must immediately cease use and remove all circumvention devices and delete all unauthorized or pirated software from their PlayStation 3 systems.
In other words: get caught with custom firmware, find yourself banished from the PlayStation Network forever. Seems rather reasonable. More reasonable than, say, filing a motion in court for the usernames and IP addresses of everyone who posted comments on Geohot's YouTube video. Read the entire statement at the source link.