I just use DropBox. AirDrop is a great idea poorly executed. It requires both Macs to be on Lion, with WiFi (Have to turn on a hidden option to allow Ethernet), both Macs have to have the AirDrop folder open and the receiving end needs to approve the copy before it does it.
For one thing, there should be an option to allow trusted Macs to just drop files onto the machine. Second, there's no reason to require the folder to be open. What is it, an application? It's a folder with a special use. Just let the copy happen without it being open. Third, why only WiFi? I get it, you like wireless, but my network is only G, so I have my Mac mini connected via Ethernet to cut down on the traffic use. Why make us turn on Ethernet ability? The Lion thing I get of course. But the rest is just silly. I pictured AirDrop much differently. DropBox works much better if I need to copy a file to my other machine without worry.