Update - January 6: Portal: Revolution has been delayed, mere hours before the conversion mod was supposed to be unlocked on Steam.
Modding team Second Face Software published a blog post to clarify that "the game is done" and could "ship at any moment, but Valve has yet to review and accept the game for release." Second Face attributes the long wait to the holiday period that has Valve running with a skeleton crew, although the wait shouldn't be too much longer since the storefront is supposedly reviewing the mod now.
