Just an update for everyone -
This attack, and our investigation of it, is ongoing. We are not the only site affected, and the breach is more recent than originally thought.
Regardless, our advice to users is the same, and the API reset tool is now available.
We still do not think passwords are affected, but would recommend changing your passwords for MCBans, the forums, and any passwords you have on bukkit.org, as a precaution.