This post talks about the large number of transactions added to the network by Satoshi Dice. Much of the discussion in the thread is about "pruning" or "compressing" the block chain so it doesn't take up as much space on nodes' hard drives and get unwieldy as number of transactions continues to increase.
What would it take to do that? I thought I remembered hearing that for any changes made in the protocol, unanimous adoption of the new client by all miners would be necessary. Requiring unanimous adoption seems like a good way to not ever get any changes done because all it would take is one person to not update, or gum up the works just because.
Or maybe I understand it incorrectly.
What would it take to implement a block-chain pruning solution?