Bill Gates, the world's richest man and the co-founder of Microsoft, is finally catching up with the world of social media. He's opened a Twitter account and set up a Facebook fan page.

Gates sent his first Tweet last night, stating "Hello World. Hard at work on my foundation letter — publishing on 1/25." The foundation is his Bill and Melinda Gates Foundation, the world's largest non-profit organisation. He followed that with a message to Ryan Seacrest, the American TV and radio host, regarding money raised for Haiti.

On Twitter, the philanthropist and Windows maven is following a total of 40 accounts, including the Economist, The New York Times, Barack Obama, Queen Rania of Jordan…and Ashley Tisdale, the actress from High School Musical. In the first six hours alone he accumulated over 70,000 followers. He can be found @billgates on Twitter, or www.twitter.com/billgates.

Currently he has in the region of 170,000 followers but this is going up by the minute.

Earlier today Twitter went down due to being over capacity, provoking media reports that Gates' joining may have had something to do with it.

Considering Twitter is being used to keep people up to date with the tragic goings-on in Haiti, however, this may have much more to do with the micro-blogging service being temporarily out of action.

Back on Facebook, too

Gates is obviously taking a very serious plunge into social media, since he's also back on Facebook after closing last summer. Back then he claimed then that he felt overwhelmed when more than 10,000 people wanted to friend him on the site.

Now he has fan page on Facebook that lists over 55,000 fans and includes photos of his Indian trip, and of his high school, Lakeside School in Seattle.