Minecraft is a single and/or multiplayer sandbox block based building game.
Use of Procedural Content Generation Methods
The levels are procedurally generated in the single player game using scaled 3D Perlin noise with linear interpolation. The scaling is done from a performance point of view but has the advantage of eliminating single block fragments. Biomes in Minecraft are built from a Whittaker diagram which you can see sketched out here.
PCG Wiki References
Terrain Generation: Part 1 - Article about terrain generation in Minecraft.
Biomes in Minecraft from the Minecraft wiki.
Minecraft - Wikipedia entry for Minecraft.
Browser Game Pick: Minecraft - Review on TIGSource.
The Word of Notch - Developer blog.
Simply Splendid: Minecraft Multiplayer by Jim Rossignol at Rock Paper Shotgun.