How can you tell that location-based social networking service Foursquare is entering the mainstream? Well, movie stars who became governors of California using the service is a very good clue in that direction.

Yes, you can now find out Arnold Schwarzenegger’s whereabouts on Foursquare. He already has over 1000 followers, which is no wonder considering his Foursquare account is advertised on his official page.

It’s a good sign for Foursquare. When Twitter started showing signs of greatness, the debate whether it will ever become a mainstream service raged on for months. Now, Foursquare seems to be entering this stage of development. What do you think: will Foursquare ever be a truly mainstream service? Please, share your opinions in the comments.

For more mobile coverage, follow Mashable Mobile on Twitter or become a fan on Facebook

Reviews: Facebook, Foursquare, Twitter

Tags: foursquare, governor, Schwarzenegger