A secret map called Pier 17 has been appearing on playlists for the recent demo of FPS Crysis 2. A developer of the game has gone on record saying that “this is not in error, but due to us testing playlists and backup. This other map will not be widely available in this demo period, and therefore you will not be able to unlock it yet. During this demo and the period up until launch we will be adjusting and balancing the game and fixing bugs, and we will announce in the coming days what happens after the end of this 360 exclusive demo on Feb 4th.”
Thanks to CVG for the info.