Assuming you could prove the IP of the laptop you would still have to demonstrate that a particular transfer went to a particular IP address. How can you do that? When transactions are verified, I don't think the verifying clients know the IP address of the recipient do they? The bitcoins go to a bitcoin address, not an IP, so how would you even find out an IP address at all?
The problem with anonymity in Bitcoin (depending how you look at it) is there can be an easy data trail for anyone interested. Bitcoin is called pseudo-anonymous because identity isn't directly linked to transactions/addresses, and it can be cumbersome to unscramble, but that doesn't mean identity can't be linked.
You're right that the blockchain doesn't record IP address info but that doesn't mean that
nobody does. Take a look at this page for a recent transaction:
https://blockchain.info/inv/0000000000000000156306d6b1a1b241dad7b87ef34a2046c7d135cdabd617e5Anyone sending transactions from their own node can be identified fairly easily if anyone is interested. In the case of Ulbricht, though, I'm guessing they have the private keys, and therefore the public keys involved in all historically recorded transactions, on that laptop. To really get paranoid grab an address you've used before or know about and
check it here.
Well, since bitcoins are not actually stored in a wallet, my interpretation of "transferred to Ulbricht's laptop" is "sent to an address whose private key is in a wallet on his laptop."
Yes, this is what I think too.
Edit: the link above was actually a block;
here is an IP page of transactions
