This has been in place in several airports including DCA. I've only seen it in use in DCA but not the others I've seen it installed at just yet.

As for boarding...that's been the case at IAD for several years now. I don't get how they can't check for your passport on an int'l flight since UA gets fined and has to transport you back at their expense if you arrive at the destination without the proper documentation. And since you aren't required to show your passport at TSA security check for international travel then there's no guarantee you have it when you board the plane. Maybe it was just a lazy GA the above poster was referring to but it should be checked on all int'l flights.

-RM