Time Warner (the third largest ISP in the US) is looking to become the first major ISP to impose billable usage caps.
After what Time Warner is calling a successful test in Beaumont, TX Time Warner is now looking to expand this new cap to other areas. Alex Dudley, a Time Warner Spokes Person said "It's clear to us that customers want online video, which requires substantial investment in the network. We're willing to make that, and we're trying to find an equitable way to distribute the cost of that investment."
The problem is that the people that experienced the cap were not happy at all about it. Time Warner put a 5 Gigabyte cap on their $30 service, any bandwidth used over that was billed at $1 per Gigabyte. I am not sure where Time Warner got the 5GB limit as just downloading the latest BETA of windows 7 would put you at your limit.
Not to mention that most movies are in the 700-800MB range, meaning you would be able to watch maybe 5 online movies per month. This is if you do not touch anything High-Definition.