Arnold Schwarznegger, the governor of California has joined Foursquare according to a tweet. Schwarznegger has over 1,000 followers on the geolocation service already [Foursquare profile] and it appears that he joined on April 21st. On the office of the Governor homepage, it even says to follow him on Foursquare too. I knew Foursquare went mainstream when we saw how much the service grew during the SXSW conference, but to see a major political figure endorse the service is a whole different story. Below is a screenshot from the Governor’s website.