I don't follow the first part; mainly because Air Sharing and the attachments you get from e-mail don't mingle. That part annoys the living daylights out of me.

And sending a file? Well, think of Air Sharing more like the "Use as HDD" option that the flash memory iPod/iPhone doesn't have for some reason (not initially at least).

You don't (still) have access to files on the system. Even through this app. Yet.