I recently moved to Nashville and signed up for the AT&T gigabit offering which is 1Gbps up and down with unlimited data for $80 a month (what a deal).

Wireless devices cap out at around 400Mbps on Speedtest.net because they hit wireless throughput maximums. My iMac which is attached to my AirPort Time Capsule via CAT6 pushes around 700Mbps up and down. I'm fairly certain I am not being capped, just that Speedtest.net POP's probably can't push that much bandwidth to max out my 1Gbps connection.