Ok, so I figured this out a few months ago but decided to wait to post it until after 1.3.1 came out. I think (I'm still testing), that you should be able to make a teleporter in 1.3.1 using portals. Essentially, you just use wireless redstone (using sand cannons) to turn of other portals set p withing 1024 blocks of the one that you are stepping through (using dispensers and water buckets) however far away. Then, you have so that only one portal (other then the one that you are going through) is open. When it puts you in the nether, there is a pulser attached to pistons to quickly pull you out and the push you back into the portal. Lastly, because of two way portal mechanics (go through one, come out the other), you would appear at the other portal that you left on.
It may work, but through my own testing with nether portals, when you went back into the portal, it would activate the first you went through, sending yo back where you were instead of sending you to the other portal.
I know, it's a bit wordy....
So, do you think it will work?
just tested it with a three-way portal and it works!
I will post a video as soon as possible.
all i had to do was give the portal that you r ntering a 5 sec. (45 ticks) delay.