I know there's been a super-annoying bug for most of Cataclysm, if not before.
I've never come across it until late-Cataclysm, so I never took note of it.
Apparently, anytime you touch a wall, or step up onto a large rock, tree branch, etc, you can get DC'd.
I've actually seen this happen, just yesterday. I was in Stormwind City, and I was trying to do that stupid lame daily, "Orphans Like Cookies Too" (seriously, this is THE worst daily ever invented, like, Ever) when I was running into the Old Town Tavern (the one where the cooking trainer is) and I stepped up onto the railing next to the stairs down to the basement right beside the trainer and......
"YOU HAVE BEEN DISCONNECTED FROM THE SERVER"
*rolls eyes*
Seriously?
And I've also seen it in Twilight Highlands, was doing the dailies there when on my way down into one of the basements, I walked up against the wall (since those basements have super narrow passageways into them) and... WHAM, I got DC'd. Instantly. As soon as I touched the wall.
Don't get why they can't fix the stupid bug already.