That AT&T's new terms of service for wireless frowns on snagging video over P2P isn't surprising, but the fact that it effectively prohibits Slinging video to phones is mildly shocking and definitely lame.
Here's the dirty clause, uncovered by Public Knowledge:
This means, by way of example only, that checking email, surfing the Internet, downloading legally acquired songs, and/or visiting corporate intranets is permitted, but downloading movies using P2P file sharing services, customer initiated redirection of television or other video or audio signals via any technology from a fixed location to a mobile device, web broadcasting, and/or for the operation of servers, telemetry devices and/or Supervisory Control and Data Acquisition devices is prohibited.
That pretty much describes Sling in a nutshell—throwing video from your house to your phone. It remains to be seen how strict they'll be on that, but it is lame cakes in writing, at least.