Basically the ESRB rating system will now be applied to indie games, probably including Minecraft, but as usual the games will be required to display "Online Interaction Not Rated by ESRB". Meaning that when someone says "snake" in a Minecraft server, its because it is online interaction, it's not like Minecraft is coded to show snakees in text chat or something.
Online Interactions Not Rated By The ESRB