Here's whats known so far:
* Most AT&T DSL (largest ISP in the US, 15.5% of US Internet users) customers ARE currently not able to access img.4chan.org (/b/ &
r9k)
*There are a few AT&T DSL users that are NOT affected. Kansas, Florida, and Ohio are where we've gotten those reports. AT&T is a megacorp made from the smaller pieces it was broken down into in the 80s- different equipment and such.
*AT&T Mobility (Cell Phones) and AT&T Uverse customers ARE NOT AFFECTED.
*It IS NOT a DNS issue. Affected people have tried OpenDNS with no success.
*It IS very visible on a traceroute. It drops within the AT&T network.
*It DOES NOT affect AT&Ts Tier 1 backbone (major bandwidth backbone in US).
*It DOES NOT affect other servers on 4chan.
*People HAVE called customer service (allegedly) and confirmed a block, but agents have denied further info.
This isn't just some small website, either. It is a very large web community, and AT&T has decided that it has the right to arbitrarily keep its customers from accessing it with no explanation. A web forum with over a hundred million posts drops off the net for over 10% of the US - no message, just a timeout when trying to access it.
If I pay for internet access, I expect exactly that - access to the internet. Not just part of the internet, especially not the part of the internet that some paternal figure thinks is OK for me to get to. Not just websites. What scares me the most is if ISPs get away with this sort of thing and start pushing for payment in order to access domains outside of a set list (or tiered content access in general). They've already started this a little bit with their treatment of bittorrent traffic.
update:
After over an hour of trying, we finally got someone from AT&T corporate to provide a statement. AT&T has confirmed that they are “currently blocking portions of the internet site 4chan.org”, but states that they are “following the practices of their policy department.”
AT&T went on to say that they did contact (or, at least, attempted to contact, they wouldn’t clarify) the owners of 4chan. They say that they have specific reasons why they blocked these parts of the site, but they would not disclose them to CentralGadget.com. AT&T states that they have requested specific things and changes from 4chan’s owners, and that 4chan has not complied.
update2 11pm PST: block is apparently down according to people on IRC, who knows what the full story is though with respect to why AT&T blocked part of 4chan and why it got unblocked. Might be technical, in which case I apologize for hyping this up. We'll probably never know for sure, though.