Intelligence Test: How Smart R U ?

I came across an interesting and simple intelligence test. This test asks the viewer to examine and compare two pictures. The two pictures are similar but not exactly alike. It is said that a genius (according to Mensa) can spot the difference in 15 seconds. The guy that posted it said he took three minutes. It took me just under a minute. I was going to copy it here but it is a flash player file so I was unable to. Here is the link.