http://www.wowwiki.com/Greymane_Wall

"Currently, as of patch 2.2.0, a relatively large grass expanse lies beyond the Greymane Wall surrounded by steep sides.

Oddly, as seen in the top left-hand corner of the picture of the Greymane Wall, the wall seems either never to have been fully completed or to have suffered at least an attempted invasion. This might, however, also be a result from the developers reusing the model of Thoradin's Wall, which is identical to the current in-game model of the Greymane Wall.

The humans surrounding the Greymane Wall are approximately levels 18-21 and the beasts around it are approximately levels 16-17. In addition, there is a neutral weapons vendor named Wallace the Blind.

If you stand in a certain "invisible stair" on the right side of the wall, you can clearly see that there is nothing behind the wall. There is simply a path that increases to a grade of 1 foot off of the ground, then ends.

If you try swimming from Hillsbrad Foothills to get behind it, you will find that the map is innacurate. Most of the peninsula behind the wall on the map is just more sea. "

Did they take out the Invisible Stair? I haven't been in that zone since I soloed SFK for the achievement before LK