First Twitter posts by celebrities

Twitter was launched in July 2006 by Jack Dorsey and asked one very simple question: “What are you doing?” Since then, virtually every celebrity has felt compelled to answer that question. Who can forget Charlie Sheen's record breaking entry into the Twitter universe, setting a world record for reaching one million followers in 25 hours and 17 minutes, only to become a Twitter train wreck. News about the death of Osama bin Laden was broken on Twitter, demonstrating the communications powerhouse Twitter has become.  

Here's a roundup, compiled by Mashable, of some of the more notable first tweets by celebs.