The most complete version of Hyrule in Minecraft is being built one block at a time.
The Escapist has featured players building parts of action RPG series in Minecraft before - including the whole map of the Super NES title A Link to the Past and an attempt to recreate the gameplay of Ocarina of Time - but Benny Girard's HyruleCraft project combines both of those ideas in a complete representation of the 3D landscape of the classic N64. The goal is to recreate Hyrule on a 1:1 scale, and eventually add in questgivers and monsters to make HyruleCraft play as close to Ocarina of Time as possible within Minecraft. Right now, Girard has released an alpha version of his project with many locations complete such as the throne room of Hyrule Castle and Kokiri Forest.
The project is certainly ambitious but the alpha version looks extremely impressive. Recreating all of one videogame in another might seem borderline obsessive, but I respect the attention to detail which HyruleCraft currently displays.
If the project can also display in 3D, Nintendo might have some competition for its 3DS remake. And if something like SOPA passes, Girard might have some legal problems with the creators of Ocarina of Time. Watch for lawsuits people!
If you're interested in learning more about the HyruleCraft project, check out the project page here (currently borked from traffic, but it should be back up soon) or learn more on HyruleCraft Weekly on GenGame.