According to BGR, everyone with an iPhone capable of running iOS 4.3 will have the ability to become a personal hotspot, including those on AT&T network. We saw the iPhone hotspot on Verizon iPhone introduced yesterday. Android hotspots are already operational on networks such as Sprint.
The first thought jumped to my mind was "Will AT&T be able to handle a bunch of people and their friends connecting over their iPhone hotspots?" but then I realized that the same question applies to Verizon as well. Since there will be no iPhone LTE or iPhone 4G, I will wait and I will get a chance to see how others and networks fair.