The problem I have with your merchant system is that your site is extremely slow processing bitcoin deposits.
Often it is 1 hour or more, and mybitcoin did it in a few seconds.
Yes I realize the risk in this, but the services I sell are time sensitive, I cannot hold it for an hour to see if the customer pays or not.
It would be great your API could instantly tell me when a payment is received (even if I have to wait for it to be confirmed in block chain before I can spend it).
We can make that happen too, a first notification when payment is on the bitcoin network. However we cannot guarantee it'll be confirmed (that's up to miners).
What could be a compromise is if you send the confirmation when the payment has been seen on the network and actually add the funds to the account of the merchant when there is x blocks containing the payment. From what I know, when the payment has been broadcasted it is already difficult to change/undo it.
MagicalTux, mailed you.