The upcoming iPhone 3.0 update will finally bring true turn-by-turn GPS navigation apps to the iPhone. The G-Map apps currently in the App Store offer something close to turn-by-turn, but lack some essential features like voice navigation. The folks behind G-Map are updating the app for iPhone 3.0 bringing voice directions and a few other nifty features. The blog Tap Critic got an early preview, and it looks awesome. It seems there would be little need to buy a third-party GPS navigation unit: