Last week, Facebook overtook Google in terms of US visitor traffic. According to the research company Hitwise, Facebook was the most visited Web site in the US with 7.07% of all Web traffic, compared to Google’s 7.03%. This is for the week ending March 13, 2010.

If Google was the number one before, and according to Web Information company Alexa this has been the case for a long time, does that make Facebook the most visited Web site on the whole Internet? It certainly appears so.

Or maybe Google will bounce back? Judging by the 185% increase in Facebook’s marketshare compared to the same week in last year, I find that hard to believe. Google only increased its own share by 9% int he same timeframe.

Facebook is already a big money maker and this will likely increase. Its last year’s revenue is estimated to be $500 million and it is projected that this will increase to $2 billion next year. Some of the biggest advertisers are already leaving Google for Facebook. It makes sense, as Facebook’s social network allows for direct interaction, engagement and targeted advertising.

It looks like Facebook’s here to stay.