First programmable 8-bit CPU built in Minecraft
minecraftforum.net
minecraftforum.net
I think Second Life is cheating though, because you can attach scripting code to objects.
There is something beautiful about that level of meta. I would be impressed if someone built a active matrix display in it.
A. Because we can.
(I am sometimes working on a Minecraft CPU with a MOVE instruction set.)
There's also the fact that the wires transmit information only 15 tiles. It's possible to build repeaters though, but those repeaters have some lag and take up space.
The hardest part are the memory cells. A single bit, even in the optimal configuration, takes up 3x3x2 blocks.