Wi-Fi Direct is the technology that enables AirDrop on Lion, which is why it is only able to be activated on certain Macs (from about 2008 onwards). AirDrop on iOS is an interesting thought, as whilst it would speed up direct sharing between your Mac and your iOS device, the mechanics of the function are unclear.
For example, what happens to the file once it appears on your iPhone? Do you have to “open in” to save it permanently? Or would there be a temporary location where AirDrop files remain? Unlike the Mac, on an iPhone or iPad, you can’t save to desktop. There is no desktop.