Draw your own Privacy area on the map
I'd like to suggest changing the way privacy zones work.
Right now you give a location variable like a zip code and it draws a circle on the map. However if you ride a lot in all sorts of direction in major cities it becomes very easy to work out the general center of this circle and thus your house, work, secret girlfriend.
I have solved this as a user by randomly deplying privacy zones in the neighbourhood but to me this is a rather ugly solution.
It would be better if you could just draw a little area on the map you want excluded from the public eye. This is random and makes pinpointing the location that the user intends to hide impossible.