If I were to leave the SL10's blue backlight ON, would the light itself eventually die (let's say the Clie is plugged in). I'm wondering if I were to use my SL10 in the car plugged in to the lighter socket, with the backlight permanently on, if that would somehow damage the lifetime of the screen or wear down the backlight.
I'd guess not. These days back lights are white LEDs, instead of fluorescent lamps (like in laptops). LEDs are generally good for 10's of thousands of hours. The LCD should do alright too, except the temperature swings in your car may give it trouble. Too cold or too hot and it could be damaged.