Microsoft's founder and the world's richest man, Bill Gates, has just joined Twitter. You can start following him at @BillGates.
The account is indeed real: it is officially a verified account and is confirmed by Twitter's Caroline Mizumoto. So far, he's only tweeted twice and retweeted two tweets, but he's already rapidly growing in followers (it only took a few minutes for him to jump from 400 to 4000 followers).
He isn't the first high-profile tech figure to join Twitter. Recently Google CEO Eric Schmidt joined the service. Then again, he isn't the world's richest man, now is he?