Check the 1.6.6 changelogs and glitches on the Minecraft wiki, supposedly if the game is at 1.6.6, then we can do the bugs and glitches that are lying around during that version.
Actually from the looks of some of the videos and what some of the people that's played it said, it's kind of a mix between 1.6.6 and more recent bug fixes. A remember it being said in a video or two on youtube.
I don't remember.. in 1.6.6 could you do that every other ladder thing and be able to climb them still? Because you can't in the 360 version.