Depending upon how you're storing the date:
<?php
$now = time(); // Unix timestamp for current time
// Get the selected time:
# For a string like YYYYmmdd
$then = strtotime($date);
# For a string like mm-dd-(yy)yy, mm/dd/(yy)yy, mm.dd.(yy)yy
list($mon, $day, $yr) = preg_split('@\s*[-|/|.]\s*@', $date);
$then = mktime(0,0,0, $mon, $day, (strlen($yr)==2 ? (($yr <= '99') ? '19' : '20').$yr : $yr));
// Now just compare the dates:
if($now < $then)
// Nope... sorry.... it's too early to see this one!!
else
// Okay, you can view this one!!
?>
Hope that helps. Obviously, if i knew how you were storing / sending the date(s), I'd be able to help further.