EDIT (And please re-open... I'm giving more info!)

What I excepted to happen was...:
-Teleport to my friend actual coordinates.

What actually happened was...:
-This happened again... in a friend server... he used the .jar (or the ''log'') to teleport me, and guess what... random location.

Steps to Reproduce:
0.- Make sure that your MC is unmodded (Well, I guess so...) and that you are in a Vanilla server (Bukkit and plugin free!).

1.- Enter the server.

1.1.- Make sure that anyone is disconnected.

1.2.- Make sure that you know your friend's coordinates.

2.- Make that your friend uses the command /tp (Example: /tp <your_name> <friend's_name>)

3.- Check your coordinates.

Another Information:
-I checked with my friend over and over and we found that it only works in ''stable'' versions (Like 1.4.2 to 1.4.7 (Will edit Affect Versions(Cannot edit)))

-I did not attached the crash because my friend did not opened the server.

Hope this works better or more than the past time.