cogadh: Nope, the closed beta started in August 2008, I'm pretty sure we already passed the actual 1 year mark.
Wolfox: Early Access Beta started effectively on September 8th, IIRC, and it went to unrestrained public Beta in late October (October 28th, I think). It would be fun to know which date would be GOG's "official" anniversary.
Considering we have members here with registered dates of August 2008, a September launch date seems impossible. The original closed beta was scheduled to begin on August 1st of 2008, but it was delayed by a couple of weeks into mid August. The initial public beta started on September 8th and the open beta started in early October. My reg date is October 1st and I was not part of the initial beta group.