Dourado is right -- but only in the same sense that physical cash transactions "aren't reversible".
Which is to say that:
a) Once the transfer is made (of physical cash or bitcoins), then only a big show of force against the right people can reverse it.
b) But you can still layer an escrow particle on top of bitcoins and physical cash to extend the window of (non-forced) reversibilility.
It's still meaningful to say that bitcoin transactions in themselves, per the protocol, are irreversible.
(And it's still stupid to promote Bitcoin on the false, flaky grounds that somehow makes chargebacks impossible, even if the parties agree to enable them.)
Which is to say that:
a) Once the transfer is made (of physical cash or bitcoins), then only a big show of force against the right people can reverse it.
b) But you can still layer an escrow particle on top of bitcoins and physical cash to extend the window of (non-forced) reversibilility.
It's still meaningful to say that bitcoin transactions in themselves, per the protocol, are irreversible.
(And it's still stupid to promote Bitcoin on the false, flaky grounds that somehow makes chargebacks impossible, even if the parties agree to enable them.)