I am only interested if it is focused on bitcoin (understand it must take fiat too), not some replacement coin.
They have their own currency called Ripple or XRP, but you can trade between XRP and BTC, and between either XRP/BTC and a number of major world currencies. The good thing is that it provides a payment system without the exchange rate risk of BTC and a distributed exchange that can provide a robust and resilient alternative to Mt Gox for getting BTCs into the real economy.