A lot of collaboration on a decentralized DNS by the bittorrent community is occurring here:

http://dot-p2p.org/index.php?title=Main_Page

The brainstorming session is here. BitDNS/Bitcoin could provide them with a lot of the source code needed:

http://dns-p2p.openpad.me/1

Real ID, reputation and waiting periods should work. Anything less is a pipe dream. The big problem here is that bitcoinmarket doesn't appear to offer any of this. Mt. Gox at least has the waiting period so their exposure is less (losing the difference between buy/sell price of reversed transactions).

I think this is a necessity if bitcoin is to gain mainstream acceptance. The rules and laws of the First Realm must be obeyed when crossing into and out of the Second Realm. Here is a  chart illustrating the concept:

BTC <-> $ =  FIRST REALM: Real ID necessary for tax reporting for any entity to exist legally in the "real world". Also provides legal accountability for large transactions. No entity can avoid this and hope to exist in any large scale.

BTC <-> Goods and Services  = SECOND REALM: Tax reporting may or may not be required and is largely unenforceable if it is. Parties can remain anonymous if they chose.