That's what Bob Cesca called the idea that Cho Seung-hui was reenacting the movie Oldboy when he massacred all those people at Virginia Tech. I agree.
First of all, the 'evidence' is one picture of him brandishing a hammer, like Choi Min-sik does in that movie. I counseled everyone I know in Korea that Americans are smart enough to know that this is a home grown violence problem and that no one would be stupid enough to try to make a connection between Korea, Korean culture, and Cho Seung-hui, but obviously it's true what they say about underestimating people's ignorance and stupidity.
Oldboy had nothing to do with this killing. The scene that they claim the picture is reminiscent of is one in which Choi Min-sik, having been imprisoned for 15 years in an illegal 'private prison', fights his way back in through a long corridor of thugs armed only with a hammer. It is something truly amazing to behold, and if you were a psychotic young would-be murderer you may seek out such entertainment. The picture shown in the above link doesn't even show Choi Min-sik's character, who never, if I recall correctly, holds a gun.
This kind of thing really disappoints me. Incidentally, here's the scene. Enjoy.