Yeah I love leveraging Ripple here! An important point to make is that there's a good chance there won't be a trust network between any random cafe and customer initially. This is where a mybitcoin.com type clearinghouse could come in handy. If both customer and merchant trust mybitcoin, then they're good to go.

What's really cool is that mybitcoin could have a trust relationship with a bunch of other "banks", and then if the merchant and the customer trust any one of those banks (and they don't have to be both trust the same bank) they can instantly transact with each other.

Yeah, it looks really interesting, but not as a competitor to Bitcoin, but as a complementary technology. It reminds me a lot of Open Transactions.

Voucher-safe isn't a distributed store of value, it's a distributed representation of the store of value. You still need a trusted issuer (or many of them) for the vouchers. These issuers in turn could store the value in gold, in bitcoin, or in anything else. Of course bitcoin has huge advantages here as it would enable anybody in the world to audit the issuer and keep them honest, and would save them huge sums of money on vaults, guards and transfer costs.

It adds a few advantages to the bitcoin system alone: real, built-in anonymity; instant guaranteed payment; a choice of different backing value stores.

My understanding of this stuff is still pretty precursory, but I think adding Ripple to the mix could be a game changer: enabling small, local transactions without the need to exchange fiat currencies. This is huge, because getting bitcoins or digital gold is currently infeasible for small transactions, whereas with Ripple, you're in the game out of the box. All you need is a friend on Facebook. This is exactly the kind of convenience that can kickstart a revolution.