They were doing this at my local Target yesterday too. I'm not sure how well it worked, because after seeing that huge line, and over-hearing there were three registers open in electronics, I headed back there to 3 reasonable lines.
I have to commend Target for their management of the outside lines pre-opening. They had police and several Target security personel out there. The security guy went all around the line, which ended up going down the side of Target, across a parking lot, and up the side of Dick's, telling people where stuff would be. He said to not run, but walk fast; not to take anything from anyone's cart; and that they'd do their best to keep the people who were sitting in their cars, or just hovering around the front from rushing the doors. They did! It wasn't until every single person who bothered to line up was in the door until they let the other folks in. Everyone was well behaved from what I could tell. Good job, Target!