I spent the last couple of days playing with the brand new i7 MacBook Air and I have to say it is an incredible piece of hardware. The form factor is perfect and the speed/functionality is unlike anything I have used. I am a happy owner of a 13" MacBook Pro (Core2Duo model) but the i7 MBA absolutely blows it out of the water. Between the beefy CPU and usage of flash memory it is absolutely a joy to work with.
Applications like iTunes, Safari, TextMate, open almost instantly, by the time you blink the app is open and ready to go. The device awakes from sleep mode in no time what-so-ever and the boot time is incredibly fast.
It almost sounds like a joke but I can safely say that the best Windows experience I have ever had is with this device. Using VMWare, the MacBook Air is a great platform for Windows 7. I should note that I rarely have a use for Windows but sadly I am working a lot with Crystal Reports / Business Objects lately which requires me to use a Microsoft O/S. Applications that typically take 30+ minutes to install on a Dell Windows machine are installing in < 10 minutes on the MacBook Air, it's really incredible.
I highly recommend this device for anybody who uses their machine on the go. I have yet to discover much (if any) advantage in using a MacBook Pro over the Air and between the portability, speed and functionality of the Air I think this is the machine to own.