Ah, I hadn't noticed the "Project Development" board until my thread was moved here  

The proposal above has the following aspects of the ideas discussed on https://bitcointalk.org/index.php?topic=172705.0:

• one global order book (backed by consensus block chain)
• order matching occurs periodically (when order book block filled)
• multiple brokers (traders specify the broker(s) they trust)
• no coloured coins or new currency required

I didn't anticipate the need for trading between ClearingHouses / Brokers / Gateways - perhaps I missed somthing?

As freequant points out, yes, I broadly agree this proposal is a "subset" of Ripple.

But is that necessarily a bad thing - Ripple suffers from:

• being centralized (at present)
• being proprietary (at present)
• not being in widespread use (at present)
• solving a much bigger and more abstract problem
• introducing a new virtual currency with some dubious "pre-mining"

I just think it would be a shame to see all attempts to design a decentralized exchange abandoned in the hope that one day Ripple will take off ...

tumak - Yes, I should have said P2P rather than merely decentralized. I guess I will have to think about "conditional block withholding attacks"!