Talking at Macworld Asia, state-owned Chinese carrier China Unicom claims that Apple's iPhone 5 will run on suppafast HSPA+ networks. It's not LTE, but that's a 3x increase: a maximum download speed of 21Mbps compared to the current 7.2Mbps.
Both AT&T and T-Mobile have HSPA+ networks, so American users would be able to enjoy this speed bump (well, in the case of AT&T, who the hell knows what the speed would be). The same is true in Europe.
It's logical to expect this to be true. We are very close to release now and China Unicom has a close relationship to Apple.
We didn't expect the faster, true 4G LTE to be supported by the next-generation iPhone. The technology has been ignored by Apple so far because it would make the iPhone too thick and consume too much battery. In fact, Apple's CEO Tim Cook has already said that they are not adopting LTE any time soon. [PC Watch via Macotakara via AppleInsider]