Quote Say your opponent has a KM out and 5 enchantments, and you have a KM and 5 enchantments. You cast CM. All enchantments die, then your opponent's KJ triggers, and since you have no enchantments on the board, he destroys your lands. CM brings back all your enchantments. After all the dust has settled, you should have all your enchantments in play but no land while your opponent has no enchantments but all his land.
Is this right?
Almost. Your opponent's Karmic Justice effect does go on the stack, but must wait to resolve until Cleansing Meditation is finished. You cannot play more effects in the middle of an effect resolving. Meditation behaves the same way as Balance in that regard; you cannot respond in the middle of Balance's individual parts because it is all part of the Balance effect.
The Meditation would complete with your opponent's Karmic Justice still on the stack. They would have their pick of any of your permanents.
--Ben