Very interesting knowledge from this topic, so its actually possible to listen to for example Satoshi Nakamoto known addresses and wait from which IP it will be propagated. It would tell nationality of Satoshi.
Not really. Satoshi could push the raw tx directly on
https://blockchain.info/pushtx, behind VPN and Tor.
I've always wondered, how do you route transactions through Tor? It's been a gnawing question, and I guess I just got around to asking about it.
But, assuming it works how I think it does, it would be next to impossible for anyone to figure out what nationality Satoshi is if he does route it through Tor or a VPN (Or both).
In relation to the OP's question, and as stated by DannyHamilton, you can take guesses, but it will be decently difficult to get a 100% confirmation on what the IP of the sender is. He described the whole process.