That's a lot of users that may have been compromised! Clearly, it's worth changing username and login details at that forum, and wherever else those same details may be used.

MacRumors user forums have been breached by hackers who may have acquired cryptographically protected passwords belonging to all 860,000 users, one of the top editors of the news website said Tuesday evening.

"In situations like this, it's best to assume that your MacRumors Forum username, e-mail address and (hashed) password is now known," Editorial Director Arnold Kim wrote in a short advisory. He went on to advise users to change their passwords for their MacRumors accounts and any other website accounts that were protected by the same passcode.Hackers May Have Stolen 800,000 User Details From Mac Forum [arstechnica.com]