There's a more active thread in "chat" about this.
There was a news conference today; the search is still going on, and has been expanded to cover the areas to the west of Malaysia where the plane might have been if it had turned back.
There is no official information on who the false passport passengers might have been, but at least one was of non-Asian appearance and it seems they went through normal check in and security (ruling out collusion by airport staff?). There was mention of investigation into a stolen passport syndicate, but no information on what that might mean about the users of stolen passports and the type of crime they could be involved with.