Originally Posted by mdolton

Location should be quite accurate as long as you have WiFi on (even if not connected to a network), as the iPhone uses wifi to triangulate position in addition to GPS. You don't need to be on a cellular network for location services.

Turning data roaming off will avoid any international roaming charges, though calls and texts may still be able to come through. If you really want to be sure you can just pop out the SIM and it will work just like a wifi-only ipod touch.