I was really looking forward to using push notifications, they are my most anticipated feature of iPhone OS 3.0, but guess what? It absolutely kills battery life. So much that I can't use this feature if I want to get anything more than 5 hours of standby with 3G turned on - on a fully charged battery. And that's just for keeping it on, without any notification actually coming in. It drains the battery so much that the iPhone feels constantly warm, even when on standby. Actually, it seems it doesn't even go fully in standby, since the running time and data usage (those in the phone prefs) go up even when the screen is locked and there are no apps running. Apple said push would reduce battery life by 20%, what a lie. I feel cheated.