Slightly off-topic, but it is well-known that one can embed arbitrary data in the bitcoin block chain, so you pretty much have to expect that at some point someone will inevitably insert one of the many illegal numbers into it, putting everyone running it openly at risk, regardless of the political attitudes towards bitcoin itself. I know anonymity isn't one of bitcoin's purported purposes, but I think it will ultimately be necessary to make it one because of this.
Anonymity would not necessarily solve this problem. Just because you cannot correlate 2 transactions or a transaction with a person does not mean that you cannot allow people to embed arbitrary data.
Sorry for the confusion. I mean't anonymity of operation, not of transactions. The anonymity I'm talking about could be achieved by running Bitcoin over Tor (which most people don't do yet, and which clients aren't really designed for), or integrating something like Tor in the client. Either way, the possibility of such an attack (an "illegal number" in some jurisdiction), IMHO, means the Bitcoin community has a vested interested in anonymity of those running the client. Of course, that's also true for political reasons... Politicians and banks already don't want an unregulated currency. However, I still view that as hypothetical threat to Bitcoin, whereas illegal numbers pose an immediate threat: anyone with Bitcoins to spend can insert something that would make running the Bitcoin client (participating in verifying the blockchain) a liability. The easy example is illegal pornography, but people could also use it for state secrets, which would likely get a more forceful military response. This could cause a massive market crash in a heartbeat, with very little skill. IMHO, it's bound to happen as soon as someone finds himself in a position to profit from a total Bitcoin crash. It's a glaring Achilles' heel.
