The days when you could say "I'll be off email; I'm flying" are ending - Gizmodo reports from the air:

I'm live from Virgin America's Beta run of their Wi-Fi service, over San Francisco, and there are a few things you should know about how its going to work when most airlines go live in 2009. And yes, I am posting this live from 15k feet over the Pacific Ocean.

This is only useful if you have power, of course. I know there will be a stream of luddites complaining about how "this last bastion of peace" has been breached, but the availability of WiFi sounds very cool to me. It will certainly make the next trans-pacific flight I have to take more enjoyable.