content: Yep. They can get reasonably precise location information (resolution reliably on the order of a couple of neighborhood blocks) with nothing but your phone transmitting.  Even a simple beacon, not even enough to keep an active connection, is enough.  Doesn't matter if your phone is off or on, what it's doing, etc.  Many (most?) phones will do it even if the OS turns the transmitters "off" with airplane mode.  The only way to be sure is to make sure it doesn't have a power source connected by removing the battery.