Not all roommates get along. Some do become best friends, and others don't get along at all, to the point that they prefer to pay money to switch to a new apartment after a month or two. A lot of roommates can go days and sometimes a week or longer without seeing one another, because of crazy work schedules. The odds are likely that while you'll do some things with your roommates if your work schedule allows it and you guys get along, you'll probably spend most of your time with people from your work location.
You will hear stories about people keeping in touch with their roommates, though. Even if you don't become best friends, with things like twitter and facebook it's easy to keep in touch after the program ends.