ok so the address it's traceable. but trace to what? no isp no psychical address
If you can trace it across many transactions, and several of those transactions have the same IP, it could be assumed that that IP is where the person is. Obviously this isn't always true, but it often can be.
I thought Ips weren't attached to txs...at least in the block chain. my understanding is that the client echos other txs it hears from neighboring clients..and when it relays those txs, it 'sounds' the same as when a client originates the tx. thus w/o active surveillance of the network (running dirty nodes) its tough to see where a tx may have originated.
There is also an option to route this traffic over TOR, in the next or the one after version, this TOR support is scheduled to include peer discovery and the ability to run all traffic thru a hidden service.
It does relay all transactions, but you never know whether yours will be detected by a service that collects IPs first, or whether it will be relayed before it gets detected by such a service. Probably half of my transactions on blockchain.info show my IP, and the other half show random nodes that relayed my transactions first.
And yes, Tor will make IP correlation impossible, if used correctly.