Pull the screen forward so it is at a 45 degree angle to the keyboard. That will provide plenty of light to the keys. Main downside: You have to put your nose on the trackpad to see the screen.
We're having some fun at Apple's expense but, seriously, why did Apple drop this very popular feature from the 2010 MacBook Air? It can't be to save battery life. You can always turn the keyboard lighting down or off in conservation mode. It might be to keep the cost down but when I'm paying $1799 for the top model, I think I should get keyboard backlighting.
Two engineering sources have suggested that thinness trumped backlighting. They say there just wasn't room to include it amongst the other components crammed in. If this is the case, fancy form overruled useful function.
I predict that when Consumer Reports tests out the MBA, they will withhold their recommendation because of this omission. Then Apple will be forced to hold a press conference with a hand picked group of journalists to explain why they left this feature out. When that doesn't satisfy the cult of the Mac, they will announce a free LED flex lamp for all buyers of the 2010 MacBook Air.
We found a clever USB powered keyboard illuminator for the 2010 MacBook Air's keyboard and standard Apple keyboard -- both of which lack backlighting. It's the Logiix USB Flex Lamp with red LEDs. It's pricer than some LED flex lamps, but the red LEDs are less harsh than the white LEDs some flex lamps use. And the 10 LEDs are spread out on a tube so the light distributes better to the whole keyboard.