After thinking about the idea for using multisig to simulate exchanging crypto and fiat (see the link in my signature for the idea), the best way I can think to do it is in several steps.
1. A party makes an offer, including price, amount, collateral (with a specified txout), an expiration time, boundary information for the window and possible escrows.
2. A counterparty accepts the offer by determining the rest (counterparty collateral and which escrow), writing the full terms in (formal) text, signing the text, and creating a tx with the appropriate 2-of-3 tx with a hash of the contract text in the CLAMspeech. No one signs the tx yet.
3. The party accepts this by adding his/her signature of the contract text.
4. The escrow accepts this by adding his/her signature of the contract text.
Only now do the party and counterparty start signing the tx.
5. One signs the tx.
6. Another signs the tx and publishes it.
The contract text would need to specify that it's void if there's not a tx with the contract hash in the clamspeech published by time X.
Unfortunately, I can't believe very many people would prefer trading with a 6 step process over simply trusting a third party exchange. Unless this could be simplified significantly, it's probably not worth implementing.
On the other hand, now that I've started looking into the CLAMour code, I'm imagining other potential uses of CLAMspeech. For example, another proof-of-stake coin could be "merge staked" with clams. Suppose the other coin (which I'll call "othercoin") is also proof-of-stake using its own token. When othercoin stakers make a new block, the block header hash could be published in the CLAMspeech of a coinstake:
othercoin
For the othercoin block to be correct, the timestamp would have to be earlier than the time stamp in the Clams block where its hash was published. Also, the hashes would be required to be published in order.
An advantage of this is that someone couldn't silently make a separate long othercoin fork (since it would be visible in the Clams chain). To be more precise, they couldn't silently stake a separate othercoin history without also silently staking a separate Clams history. It would also rely on timestamps in Clams blocks to prevent attacks by falsely claiming an othercoin time in the future, unless they also attacked Clams this way at the same time.
Would there be any objection to this on the Clams side? It seems like it would give more people a reason to own and stake Clams.
The only downside I can see is that it restricts stakers from making clamour votes. It seems like "othercoin " might only take up about half the CLAMspeech, so people could still vote for some clamours by having a speech like:
clamour othercoin
PS: I now have two testnet clam nodes running. For testing, I need to be able to stake fairly regularly, so it would help if someone could send massive amounts of testnet clams to n422ULsfpah4GEJciZ1uRYMCLgFdGCpBsP and mxHPD9KUvyvezaVC87b2vFrnHaiFnB44mf. Based on the current staking weight on testnet, it looks like approximately 100,000 clams would let me stake a few times an hour.