a properly set up distributed exchange shouldn't have a central entity that can grab them.
I agree.
Seems to me that, in theory, a completely distributed system based within the block-chain should be doable. Perhaps with an overhead cost, per-trade cost, being whatever the going rate is for a BTC transaction of equivalent value.
This would create, perhaps, an incentive for an application, beyond bitcoin-qt and its equivalents, which enables tracking and performing trades of assets which are tracked/verified/validated by 'transactions' embedded in the chain. (And possibly opportunities for a web site(s) which support this for those who don't want to 'pay' the overhead of running a full bitcoind and its giga-bytes of data. Which, of course, would be entitled to a, small, additional percentage cut per trade.)
Hmmm, probably still needs 'exchange' sites where buy/sell bids can be submitted/moderated to allow for 'market' establisment/fluctuation. But with such a 'chain-embedded' tracking of assets the current issue of divorcing issues from validated holders of shares would never again occur. And since up to date ownership of shares is never in doubt, they could readily be traded at *any* existent exchange. Hence creating motivation for exchanges to compete by the services offered and fees charged with no risk that an 'exchange' can abscond with the assets. (There would always be risk to any transient BTC held by an exchange, but the assets themselves would be safe.)
I think some work has already begun on something like this but it is immature to date. If anyone else recalls such please reply with a link. I might be interested in personally putting some software dev man-hours towards such a solution.
