The resource world access is now available. The departure facility is beneath the existing stargate, with the entrance on the west side of the hill (on the road to the nether portal).
This is just the resource world, as previously discussed. It's a small world intended only to provide us access to the new resources introduced in 1.5.1. As new resources are added to the game, this world will be entirely replaced and nothing will be saved from it. That means don't go spending a lot of time building structures, because they'll go away at some point.
There is a small chance the teleportation procedure will kill you. If that happens, let me know and I'll re-calibrate it.
This is not the "super-survival" world as was also discussed. The difficulties of using the same world as both the resource world and the "super-survival" world, largely in the one-way inventory, were too much, and the super-survival folks probably wouldn't appreciate normal folks showing up and stealing all their resources anyway.
News about the "super-survival" world will be forthcoming, and will coincide with the mothballing of the old world.