What's behind the Twitter celebrity bloodbath?

Twitter has many uses. One recent popular use is to use Twitter for spreading false rumors about the death of celebrities. In the immediate wake of Michael Jackson's death which itself was preceded by a false report) it was reported on Twitter that actor Jeff Goldblum was killed after falling off a cliff in New Zealand. Then the celebrities started dropping like flies: Britney Spears, Ellen DeGeneres, Miley Cyrus, P Diddy, Harrison Ford, George Clooney and even Rick Astley. Some involve hacks. Britney Spears' Twitter account was hacked in order to announce her fake death. What's going on?