No, it was truly hacked. PHPBB has some security issues and a new exploit came out about 2 weeks ago that would give out admin password to anyone who sent the right URL. Fun, eh? On top of that they didn't trash anything, just removed the admin privileges for the top 4 people.
And generally speakin', 9 times out of 10 when a site gets hacked it's due to a beef with the Sysop...just like 9 times out of 10 if you're a victim of ID-Theft it's somebody you know.