Actually, you're right, I'm not all that sure.
It depends on the deal with the publisher, if there is one, and I have no idea what terms Jonathan Boakes has agreed to.
However, it does make a big difference if you're an indie developer like Amanita. You can download their Machinarium on Steam, buy a German/Russian/Italian boxed copy. Or download it from Amanita's own site, which is the most profitable for the developers.
