Minecraft needs a "Fortress Mode" :)

was reading Minecraft's original TIGSource forum post and saw this:

"Fortress mode

After having built a level in Creative or Survival mode, you and your friends connect to another fortress made by some other people. The map gets bigger so it fits both maps, and you play a game on this map. Perhaps Capture the Flag, perhaps something else"

WE NEED THIS IN MINECRAFT! (please just put it in both versions at the same time, I don't wanna have to wait in between updates if Java gets it first)