SMTP
As we all know email accounts can somehow talk to eachother and that way it doesn't matter if you have a different provider, I can still send you an email. So surely the samecan be done for cryptocurrency, the question is what would be the easiest way to get itdone? 
Ripple
With Ripple it's allready possible to send somebody BTC, while I hold XRP. Besides BTC'sthey have also added LTC, but unfortunately you can still not send LTC (LTC has been onRipple for months now, without being activated). This is also a sign, that we are not thinking in the right and a social way about eachother. This is why I can't call Ripplean social money transfer protocol. What chance do we stand if we don't open up the doors to eachother, the establishment wants to keep us out, the key to successs is allready in our hands. Think about it, if Ripple would add 200 cryptocurrencies, toit's lists of currency, we could all instantly send money to eachother. From Dogecointo Peercoin etc... Every cryptocurrency in existance with a minimum marketcap of$10000 should be added to Ripple. If you don't think this is powerfull, start thinkingof the marketcap as a totalsum of all the included crypto's.
Social Money Transfer Protocol
Let's say that Ripple doesn't want to play ball, what would be a way to send eachother money?It's only today that I started thinking about this, so this might not be an elegant solution or anpossibility. Let's say that Andreas got Dogecoin and wants to send Amir Bitcoins (always usezero's or hero's in your example). How would an Social Money Transfer Protocol work? We need to keep 3 things in mind. 1 (Sandbox) Bitcoin and Dogecoin are not in the same sandbox. 2 (Oracle) We need an oracle to sign for the incoming and outgoing money. 3 (Donator) We need somebody to make money available, in return they receive a fee.
Bitoverrated.comBitrated.com got a multisig solution which enable Alice and Bob to send eachothermoney with an arbitrator incase something goes wrong. What if instead of humanswe had an oracle and multiple cryptocurrencies? 

Andreas first picks an INPUT currency (The oracle gives him an Dogecoinsaddress) than a OUTPUT currency (Andreas enters Amir's Bitcoinaddress), now he's presentedhis INPUT, OUTPUT and a fee for the DONATOR of the BITCOINS. He sends the Dogecoins this is signed by the oracle so he can't take the money back. The oraclesigns the OUTPUT and Amirs receives the Bitcoins. The donator receives the Dogecoinand a small fee.