I'm a first time iPhone user and I've been reading up on how to "close" or "exit" apps, apparently some apps run in the back ground and can drain battery life. I guess on the iPhone 3G you could just hold down the 'home button' for 5 seconds or so and it would exit the app but with the 3GS if you hold the 'home button' for 3-5 seconds the 'Voice Command' feature activates. Is there a different way of closing Apps now?