I usually don't answer my own question, but in this case I have to I guess.
I am running Minecraft pre-release 12w36a and I can confirm that you can cure infected villagers spawned from dungeon zombie spawners in survival mode.
I had a zombie spawner underneath my base that I never destroyed, I am glad I kept it. I set up a small killing device for killing the unwanted zombies, and waited for a infected villager. In my case it spawned one every 30 zombies or so.
When I got one I used a splash potion of weakness (water bottle + fermented spider eye + gunpowder). As soon as I threw it I got my golden apple in my hand, and just right-clicked the villager. At this point he started shaking.
While he was shaking, I waited around. About 5 minutes later he turned into a normal villager.
At this point I wanted to know if he would despawn, so I went exploring in my world, slept for a few days, and went to the nether a few times. When I came back he was still standing there, which was great.
I do not know if this will stay in the game. I will update the game once in a while to see if it still works in the snapshots.
For now I will work on setting up my village, I am glad I don't have to build the 1000+ block railway anymore.
I can confirm this works in 1.4.2, see the video in the question for more details.
By default, a 21 chunk by 21 chunk area (with the player at the center) is loaded for each player on a server. The simplest solution is to build your circuits so that they use both vertical and horizontal space to fit them within that area. If this is not possible, then you will need either a plugin (bukkit server) or a mod (vanilla server) to manually load the chunks. It is important to remember however, that this will cause an additional load on the server, so the first solution is still preferable.
Here is the mod that I use to load areas:
Chicken Chunks - http://www.minecraftforum.net/topic/909223-162-smp-chickenbones-mods/
A simple search on the bukkit plugin site will yield a number of options. I cannot suggest one over another, especially without knowing what version you are running.
Best Answer
The invisible zombie will attack you on survival, and if you're in creative the collision will move you. the thing you may first need it's the zombie (this time will be no invisible, but silent):
After, you will need add a team for
/team add zombie
After, you will need to modify the team and erase the teammate collision
/team modify zombie collisionRule pushOtherTeams
And then (optional), FriendlyFire
/team modify zombie FriendlyFire false
After, you will need add the zombie (and you). it's easy, you had to stay near to the zombie and put:
/team join zombie @e[type=zombie,distance=..3]
For you, only
/team join zombie
Final step, you will need the zombie does not stay near of your camera (player vision) Put a repetitive command block, in it:
/execute at <your name> as @r run teleport @e[type=zombie,team=zombie] ^ ^ ^-1