Block explorer: http://blockscan.com/
Official site (under construction) https://counterparty.co/
Installation instructions: http://counterpartyd-build.readthedocs.org/en/latest/
Github: https://github.com/PhantomPhreak/counterpartyd
Discussion thread: https://bitcointalk.org/index.php?topic=395761.0
Thing is what proof of * you use don't matter. You're not in control of the chain, and anybody can just spam the bitcoin blockchain with fraudulent transactions (double spends, etc.)
And the only way for anybody want to accept any of those assets, would be to calculate the probability of having a real asset in hand from the entire blockchain history that this amount derives off of.
So, very sorry to say that, but, this'll crash&burn. That's just how it is if you forgoe the iron guarantees of proof of work.
From what I understand, XCP transactions guarantee atomicity and funds are swept from addresses to fund any bets/orders immediately. The risk of double-spending XCP is the same as the risk of double-spending BTC as XCP relies on bitcoin's proof of work.
Please correct me if I'm wrong.
This basically means that XCP-looking transactions will appear in the blockchain, however, they will be invalid, because by the rules of XCP their outputs would already be spent.
In Bitcoin this is an invalid transaction, and it never enters the public ledger. This important because, it allows you to shortcut the path to figure out if an address has unspent outputs. Figuring out quickly if an address has unspent outputs or not is important for miners (they need to produce valid blocks), and it's important for participants to transactions, because it means the recepient can quickly verify that the sender is intending to make the transaction, and that a transaction, sufficiently confirmed, is not double spent. The recepient relies on the work of everybody who produced a block. And in turn, everybody who produces a block relies on the work of everybody before AND on the work of everybody after (who bases their block on his).
This is what I mean by iron-clad guarantee against a double spend.
But if nobody can reject an invalid TX for XCP, that means verifying that something has unspent outputs is an extremely expensive task. And the longer transactions go on, the more expensive this task becomes. And nobody can put in some kind of "block" that could be rejected by others to "proove" that some balances on addresses are now valid up to that point.
This means that in a short time, XCP will become unusable for everybody as the XCP-TX spam rises and everybody is checking the entire bitcoin blockchain over and over and over for XCP-looking TXes to figure out if the coin he thinks he got, aren't actually double spends.
I think this is a valid concern, even if somewhat mitigated by the 0.0001 BTC transaction fee. I'll post this to the BTCTalk thread and see if someone smarter than me has an idea to defend against it.
Proof of burn was used during an initialization phase (let's call it distributed minting) which is over. Should really check it out more thoroughly, it looks like a pretty neat idea.