[sktrdie]

No IP address is saved in the block-chain. You would need to trust the source of this IP listing service, and still you wouldn't be able to actually prove people's real IP address if they were using systems like TOR to send money.

[wdvh]

I understand it isn't saved, I meant you could connect to the network and listen in on transactions.

And what percentage of bitcoin nodes use Tor? With NSA-like global passive logging, I think even Tor could be vulnerable.