Why don't the 5 biggest mining pools (ghash.io, btc guild, eligius, slush and bitminter) publish what transactions they are including in the block they're mining? (The transactions that will be included in the next block if they mine it) That way you could be relatively sure that your transaction will (probably) be included in the next block. If you're a merchant, you can be reasonably sure there won't be a double spend, if all 5 of them include the correct transaction. (If some of them have a conflicting transaction you know that a double spend was attempted). This seems like a really useful feature. Why don't they provide it? I know that they publish the block headers to connected miners, but not the list of transactions.