The movement, led by Harold Camping who runs the evangelical station Family Radio, is predicting that mid-May of this year will bring about Judgment Day--the time when, according to some, the earth will be destroyed due to mankind's sins and all Christian believers will ascend to heaven.
Apparently Camping believes this will occur on May 21st because of a mathematical system he created to interpret prophecies hidden in the Bible.
While this prediction is pretty eerie in light of the mysterious animal deaths in Arkansas, it's worth noting that this isn't the first time that Camping has predicted the end of the world.
He originally used his mathematical system to predict Sept. 6, 1994 as Judgement Day. (via NPR)