Minecraft wiki entry for Mod_Coder_Pack, associated text: Use MCP to do anything that violates Mojang's terms of use for Minecraft.
Release Minecraft versions or modifications that allow you to play without having bought Minecraft from Mojang.
Release modified or unmodified versions of MCP anywhere.
Use any of MCP's scripts, tools, or data files without explicit written permission.
Make money with anything based on MCP (excluding Minecraft mods created by using MCP).
Use MCP to create clients that are used for griefing or exploiting server bugs.
Release the decompiled source code of Minecraft in any way.