That's odd. According to the terms of service for my Comcast service in Denver, the "bandwidth limit has been temporarily suspended". Over the last 6 months I have used between 350GB and 600GB of traffic each month and I have never received any sort of notice.

In fact, I could have gotten 40mbps DSL for $35 (special deal) but they had a 250GB/month cap and the only option to have no cap was a $175/mo for the same speed (but a dedicated link).

So I'm using Comcast specifically because the lack of a limit on bandwidth.