4G, besides not existing outside the USA, isn’t ready inside it.
Edit - of course, all these phones can use 3G as well, or even turn off 4G entirely, at which point the battery life will be better. But the point remains - you cannot yet get reasonable battery life out of a phone if you use 4G.
Moreover, the iPhone appears to beat a lot of *3G* phones by a wide margin. Interesting to see the different between the CDMA and GSM/UMTS models as well.
And, of course, if you turn off 3G and mobile data entirely the iPhone 4 will last for a week between charges.
(Chart from Anandtech)