I have done a video of the 'Secondworld' exploit for my YouTube channel.
In my video, I use a current patch 4.0.6 disconnect macro. I also avoid the whole "swimming down until the kill zone"... I just fall to my death.
This was inspired from Skuzzi's work originally posted in this thread: http://tinyurl.com/4h5j4xj
All credit should go to Skuzzi, Order of the Hidden Eye, RAOV, VotU, and those that have come before.
((This glitch is client-side. You can explore places with this glitch (like Tanaris Underwater Mine, or even GM Island, if you're creative), and you can even stay live in chat channels while you explore... but you are really not "there" as far as live server exploration is concerned.))
Thanks to Order of the Hidden Eye for first discovering Otherworld, and Arrrdolf for discovering Secondworld. Thanks to RAOV, VotU and Skuzzi for pushing this glitch forward for the solo-explorer. Last, thanks to Dontc4re for hooking me up with the Sandbox Tiger!!