OK, a Finney attack against SD, nice.

BTW does anyone know if Eclipse publishes the list of blocks they solved anywhere? I couldn't find such a list on their site. If Eclipse did solve it, then I guess Inaba needs to examine how A' got into his memory pool.

Miners that are accepting direct submissions of transactions that would normally fail to relay really should be ensuring those transactions don't conflict with any in the memory pool, and if they see a broadcast transaction that would double spend a direct submission, should take the broadcast transaction as having priority.

Is it possible to send a tx that wouldn't normally relay to a node, but still get it accepted into the nodes memory pool? I thought the code did not allow that, but maybe I'm wrong.

It seems worth investigating this in more detail.