I recall the mods here suggesting that people worried about this should post screenshots of their photos. This has been something I've wondered about too. Is it really that easy for amateur hacker types to get this data from pictures posted on websites like this, or are there more hunters out there that work for the NSA than we think?
I think it's geotagging that gets imbedded in photos. I have been told if you have your location turned off it won't be present.
I think if you know what you are looking at it's not difficult at all to come up with. But I'm not one to know.