I ran into a shooter that I used to know at a football bowl game in December, and he was using an 11-inch MBA to edit and transmit. Of course he had to use the USB port for downloading, but he didn't report any complaints. But I think he was shooting jpeg files.
Doing some research as I look to replace my 17-inch MBP, and I really wanted to like either of the Air models, but the limited RAM and the slow processor speed make them less desirable for hard photo use. Maybe if I have a desktop in the studio for the real heavy lifting, and use an Air on location, it might work.