Yes, we do really need that. What's the point of having a p2p currency if we have to rely on centralized server to exchange it with other currencies.
We need a p2p forex market for btc. Who's up for this?
I'm tempted to mention bitcoin-otc, but that, of course is (a) an over-the-counter system, not an exchange, and (b) is also somewhat centralised (one website, one IRC server - correct me if I'm wrong). Could bitcoin-otc, or something similar, function on Diaspora? My thinking is, and I've used Diaspora for all of 30 seconds, is that we sign up to various decentralised Diaspora pods (multiple pods mean that the system can't be taken down simply by taking down one pod/server in one jurisdiction) and then create an "aspect" for trading bitcoins, and friend (I think Diaspora calls it "sharing") other bitcoin traders.
This doesn't solve the decentralised exchange issue, but does create a decentralised platform for bitcoin trading.
...or am I just providing a solution to a problem that doesn't yet exist?