How can I ensure that I'm logged out of Google Latitude?
If you see "Join Latitude" then your latitude options are already "off". If you also now see "location sharing is not turned on", then your account is not set up to share the location information and it will not be sharing the information. 

If you don't already, turn off wifi &amp; gps when you are not using them, mpas will be less likely to try and get "pin point" information if you do not have these running.