I don't have two systems to try it on, but there is no reason it shouldn't work. AirDrop is just an ad-hoc network connection setup between the other computers on the network.
I've actually tried this and I keep getting a "transferred cancelled" message even though I never cancelled the transfer nor did I receive a prompt requesting authorization to transfer the file on the Mountain Lion computer
Wirelessly posted (iPhone 4s: Mozilla/5.0 (iPhone; CPU iPhone OS 5_0_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9A405 Safari/7534.48.3)