Race officials are reviewing the final few seconds of the Indianapolis 500 to determine whether Dan Wheldon will be named the official winner of the Indianapolis 500. The problem is that racing rules state that no one may pass under a yellow flag. They need to determine whether the yellow flag came out before or after Wheldon passed Hildebrand for the win.
If he passed BEFORE the flag came out, he's the winner. If he passed AFTER the flag came out, even by half a second, Hildebrand would be the winner since 1) no one was allowed to pass him, and 2) he did finish the race under his own power. In essence, the pass would not count, Hildebrand would win, and Wheldon would have the victory snatched from him because of a fraction of a second.