I always had mine set to never update. And it STILL turned the GPS on every time I would open the app and hang for like 30 seconds after I closed it. AND, on top of this there is a 30mb running service in the background at all times. Facebook SUCKS!
I have since deleted it and just use the website.
Luckily, when I did have it installed I was running Cm7 and could revoke permissions for apps. So I did so with facebook and location and it would never run. But, if your stock and can't do that the only thing you can do really is turn off GPS in the system so it won't do it or live with it. (Or delete it all together like I have done).