Brian Acton will now finally join Facebook, which rejected him a job four and a half years ago. In a tweet on August 4, 2009, he wrote, "Facebook turned me down. It was a great opportunity to connect with some fantastic people. Looking forward to life's next adventure."

This rejection came just a few months after he was turned down by the other rising social networking star, Twitter. In a tweet on May 24, 2009, Acton writes: "Got denied by Twitter HQ. That's ok. Would have been a long commute."

His next venture was WhatsApp, which shook up the world of messaging, turning users away from text messages and Facebook. The service now has 450 million users and adds approximately a million new users a day.

Jan Koum, the co-founder who has now been appointed to Facebook's board, used to live on free food stamps provided by the government when he moved to the US from his home country Ukraine, according to a report by Forbes.

Life came full circle for him when he signed the deal to sell WhatsApp to Facebook at the same government welfare centre. The difference? Instead of standing in line like so many years ago, Koum drove to the centre in his Porsche.