Speaking at a meeting of the Churchill Club in Santa Clara, California, AT&T CEO Randall Stephenson said that Apple will bring out a version of the iPhone that runs on faster 3G data networks in 2008. “You’ll have it next year,” Stephenson said in response to a question on when the highly-anticipated device would debut. Previously, Apple CEO Steve Jobs has said that current 3G chips are too power-hungry to use in the device,…