By mixer I mean a service that has coins and will send coins from its wallet when it receives coins, ensuring they are not the same.
In that case, in my language a 'mixer' is a node. Based on what you've said in earlier posts, the difference seems to be that people trust mixers but not nodes (and that mixers are more 'sophisticated'). Or is there more to it?
On AML laws, are you seriously going to go in front of a judge and try to argue that Bitcoin is not a currency and users of a mixer/mixnet are not "customers" in some way? I would be interested to see the reaction to such an argument given that the system is called BitCoin and the front page title is "Bitcoin P2P Virtual Currency".
If I try to pay my taxes in bitcoins I'll get about the same reaction as if I tried to pay them in Monopoly money. Would you suggest that the government will prosecute me for creating a Monopoly money laundry?
The (important) difference between one and the other (for this discussion) is that people seem to think Bitcoins have more value than Monopoly money. Neither is a currency in the same sense that bank notes issued by a national government are currency.
I say again that node operators will have do their own homework regarding their local jurisdiction before they start.
This is all getting a little off point. The original purpose of this thread was to solicit comments regarding the general technical architecture and operating process of a Bitcoin mixnet. Since no one has commented on those aspects I will proceed towards a more detailed technical specification and reference implementation.