The thing that's exciting about Google Fiber is what it represents -- reasonable cost, no bandwidth caps, net neutrality, etc. Google WANTS its customers to use the Internet as much as possible. The more HD videos people watch on YouTube and the more people surf the web the more ads they show and the more money they make. The opposite is true with AT&T -- they'll start metering and charging the second they can.
I'd take 100Mbit Google service over 1Gbit AT&T service any day of the week.