If only it was done using iCEnhancer http://i.imgur.com/adKTzcX.jpg
However... Regarding the OP, a Google Maps of Liberty City is really awesome though. Imagine if someone hacked the cellphone in the game to run off an Android emulator rendered to a screen overlay, and link it with the Google Navigator app (that's a significant modification to the engine though so I don't know if that would be possible, and especially not on multiplayer LOL).