Quoted from Reddit:
From what I can tell, this is only a confirmed issue in Southern California at the moment, but seems to be wider than just a regional problem. Those who have contacted AT&T representatives were told that the site is in fact blocked, so this isn’t a technical problem, and all the other 4chan subdomains work fine.
Moot is aware
It’s come to our attention that AT&T is filtering/blocking img.4chan.org (/b/ & /r9k/) for many of their customers. There is no remedy at this time.
If you’ve been affected, I would advise you call or write customer support and corporate immediately.
xkcd‘s comment is my favorite:
What IP blocks do their corporate offices have? If they’re really cutting off my trashy time-wasting web entertainment, I’m cutting off theirs.
As many people have been saying, this very well could be the begeniniung of the end of the Internet as we know it. And considering the 4chan crowd, AT&T should be ready to battle. The shit is really going to hit the fan now. Too bad for AT&T. HA.
I created these graphics. Please feel free to use them for yourself.