Can I prove that I made a bitcoin transfer to a particular address? Say, for example in case of a legal dispute. I am asking for something more substantial than a screenshot of my wallet. I understand that all transactions somehow ar stored on the network?
Then the question is, how can you prove to the person you paid that the address was one that they gave you to pay?
And the answer to that:
We need a payment protocol with non-repudiation built in.
See
https://gist.github.com/2217885 for a multisig version (the singlesig version is simpler, but the merchant <-> customer communication will be the same).
And a variation of which is being developed now. The Development mailing list has a thread on the topic.