I know absolutely nothing about GPS. From what I'm reading though - basically what the iPhone 3G does is display on Maps your current position and as you walk around the little marker moves. Is that correct? People keep mentioning turn-by-turn and the 3G doesn't have that. Is that a feature that can be added later, do you think? Is this a feature that might be available on other phones? I am still undecided as to whether I will purchase a 3G or just keep my old iPhone and the GPS function was one of the things really getting me interested in the 3G. I keep thinking back to a trip we took to NYC last year and how useful it would have been to know our current position as we walked around.