I have 5.6 and have never heard of anyone on 6.0. Would be news to me.
Ok, take a look at this thread... The last post particularly. Also I did some googling, and others have 6.0 loaded as well.
http://forum.theiphoneblog.com/ipho...4-whats-latest-official-att-ipcc-version.html
He clearly has messed with his device, there is no mistaken it is jailbroken. The official AT&T carrier file is 5.6.
If you have other links please share and I will take a look.
Ok, like I thought, it's not official. There are rumors that it activates tethering. Nothing more.