Harold Camping didn't say the world is ending on May 21. He said the end is going to start on May 21, 2011, at 6 pm locally all over the world. If there's an earthquake anywhere today, he will take the credit. Of course, I'm not sure how he will explain his lack of being raptured when he is still on Planet Earth on Sunday morning. The sort of rolling destruction he predicted, which was to have taken place at 6 pm in each time zone and then circle the world as 6 pm local time marches around the world, is not happening.
At least he is a relatively harmless former civil engineer, because he is not advocating mass suicide, as the Hale-Bopp Heaven's Gate cult did.
From Wikipedia: Heaven's Gate was an American UFO religion based in San Diego, California, founded and led by Marshall Applewhite (1931-1997) and Bonnie Nettles (1928-1985). On March 26, 1997, in a period when Comet Hale-Bopp was at its brightest, police discovered the bodies of 39 members of the group who had committed suicide in order to reach an alien aircraft which was supposedly following the aforementioned comet
I have a prediction: Sunday is going to be a tough day for the current batch of doomsday prognosticators. Then again, I suppose that Harold Camping will just go back to the calculator and start calculating a new doomsday date. After all, he explains that his September 1994 predictions were merely a mis-calculation. Wrong in 1994, wrong in 2011--maybe he of the ultimate belief that all answers lie in mathematical calculations will come to the conclusion that the third time's a charm.