 We have a beautiful wallet that we've constructed for Cardano called Deadalus, and soon after the mainnet launches we'll issue an update to Deadalus which will have a checkpoint center where anybody can publish their own checkpoints and people can subscribe to them and you choose who you trust. For example, IWGK can issue a checkpoint, Armurgo can issue a checkpoint, CF can issue a checkpoint, and if your checkpoint disagrees with the history that you've received from the blockchain that the protocol is connected to, then you and the user are given a choice of what to do, either to find another chain or to contact someone, there's a lot of options you'll have at that point, but at the very least you'll know that there's some issue with history. Now what this gives you is you don't actually have to download the entire chain, just the most recent state, so you can have much faster booting up, you can actually have much more flexible trust and you actually get to choose the people that you trust. Now this doesn't mean that the protocol relies upon a checkpoint, the theoretical guarantees are very clear and we've proven that the protocol is secure without this, this is more of a mechanism to have good engineering meet good theory and allow people to use the protocol in a much more realistic way.