I've enabled PVP mod, reset the world and inventories. In the event we dont like it etc, I have the old world / inventories backed up, so we can revert to it. PVP Mod: http://www.minecraftforum.net/viewtopic.php?f=1012&t=66496
Sin Deathsworn and I spent 2 hours digging, found like 20 linked caverns, mad loot, only like 8 diamonds...