Legend has it Old Ironforge was an open area in Beta but it took too much for the servers to run it that they closed it off. Even though Blizz is better equipted they still havent reopened the area.
If you go into the throne room which is right off of the Great Forge you will see 2 very large doors on each side of you. There is a woman standing to your left. This is the door to Old IF. You will see it is a false door and the object collision isnt exactly right with the door because you can walk into it slightly.
At one time you could walk through it as a ghost but when we tried in Aug 2007 you can no longer do this. If a hunter stands so their pet is inside the door when you cast Eyes of the Beast it will say your pet is not in your line of sight. You need to run at the door, stop right at it and your pet will continue to run forward a few feet and walk back. While your pet is inside start casting Eyes of the Beast. You will probably have to try this quite a few times to get it exactly right. If your pet isnt in the door far enough they will be caught half in and half out and you can see the hallway but cannot run your pet forward.
Below are some pics of my pet inside.