http://developer.android.com/guide/topics/location/strategies.html
Your can obtain either GPS or Network location, or two at a time. The permission to get location from Cell Towers or WI-FI is:
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />
Just register a listener and get the updates
LocationManager manager = (LocationManager)
context.getSystemService(Context.LOCATION_SERVICE);
manager.requestLocationUpdates(
LocationManager.NETWORK_PROVIDER, 60, 10, listener);