The first time a national leader was forced out using social media was in 2001 as this article states.
In 2001 Philippine President Joseph Estrada had committed some crimes and the government wanted to hide these facts. The citizens of The Phillipines would not have it and used. Upset protestors sent text messages out to rise up against this ruling, sending over a million protestors to downtown Manilla. This scared legislators who then worked to end the regime of Mr. Estrada. This is the first exmaple of where social media (text messaging) was key in ousting a dishonest President. This is a great example of how technology can help drive social change.