Unchecking "Use GPS" does NOT save battery
A lot of people think that leaving the Use GPS and WiFi Location boxes unchecked will result in better battery life. This is not true and here is why.
The "Use Wireless Networks" and "Use GPS Satellites" are permission settings. These settings ONLY allow/disallow applications to either use wireless networks and/or GPS to get the device location. These settings do not actually turn on or off any hardware, therefore is does not save any battery. Applications actually turn on/off the GPS when they are using it, and you can tell when this is happening because a GPS icon will appear by the clock. So leaving "Use Wireless Networks" and "Use GPS Satellites" on does NOT affect battery life, it is just permission for apps to get your location.
So if an app could change these permissions then their functionality is pointless, so Google is starting to patch the way apps like SeekDroid are currently doing this (stock Android 2.3.3+). We do realize that remotely enabling the GPS serves other purposes and we are working to still have this features.