does having latitude running all the time eat away at my battery?
It updates more often than that, because often when i'll sign into igoogle home, it will tell me where i am via latitude on my homepage and will give me the status like 10 minutes ago. Often times i will not have used google maps since the previous day.
That being said, if you have gps disabled, then it does the triangulation thing via cell tower info. I have not noticed a battery difference with latitude on or off.