I'm actually typing this on my 1st gen Macbook Air. While many said it wasn't powerful enough to do real work, I billed over 1,800 client hours with it the first year and it made my weekly travel much easier.

The new MBA have Thunderbolt and with the new Thunderbolt display, you get all your external ports built in (gigabit ethernet, FW800, 3 USB ports, audio, iChat/Facetime HD camera, Magsafe power). My guess is the new MBA + Thunderbolt display is probably all the majority of travelers need. Light, fast computer while traveling; a docking station with large display, at the office.