They only said the "closest guess" will win so you can still win if it comes out after your guess, so don't give up yet...
Indeed -- if it comes out after 31 Dec, then the first person who guessed 31 Dec 2004 should indeed win

because the closest guess is suppose to win. Plus one could argue that a "release date" is not for a CVS, not for beta, and not for a RC date, but the actual "phpBB 2.2" release date as noted from the rules and the entry.php page used for guessing.
Yes we all know that phpBB 2.2 is not coming out this year although the developers have and are doing a great job IMO, but I confess to having guessed 31 Dec to allow the maximum possible amount of time because only 2004 dates were allowed in the guess, but the closest guess is suppose to win. But I am sure that others guessed 31 Dec 2004 also and most likely guessed and entered 31 Dec before I did, but if not, then I deserve, demand, and want my phpBB plush bear on New Years Day, no sooner and no later...
** more seriously I also want the developers to enjoy their holiday time with family and take needed time to rest if desired. Thank God

we get a week off at Christmas from work and I surely know that the time off helps to recharge our batteries **