AT&T has recently decided they too will be enforcing “network management” protocols in the near future, looking to prevent network congestion from people saturating their connections. While they haven't gone so far as to say they will implement bandwidth caps, they have mentioned that they will be throttling download speeds during periods of heavy use, and in particular will be throttling those who subscribe to the faster speed services they offer.
They claim that they are concerned primarily with being able to deliver high-quality video through U-verse, and that these steps are necessary to “enhance the reliability” of their network. They mention they will not specifically target heavy downloaders, which means they may restrict connections from people who hardly use it just because they happen to subscribe to a faster speed service. That hardly seems fair.
On the other hand, if you are a U-verse subscriber, streaming video is a huge selling point of that – and choppy video due to network congestion would make it tough to compete with cable.