The QuakeCon Website
outlines a recent hacking incident on the old QuakeCon forums:
In recent days, a hacker carried out an unlawful intrusion of the old forums.quakecon.org site, compromising usernames and passwords. While we have taken appropriate steps to protect the new forums from attack, we recommend anyone using their old credentials on another site to change their passwords immediately.
We regret any inconvenience this may have caused, and suggest you migrate to the new forums — which will be live shortly — to discuss QuakeCon 2011.