I've been using laptops mostly for the last 4 years. I've had 3 of them. I notice that, when new they are bright and crisp and white, but after about a year of heavy use, the picture starts to fade and yellow a bit. Which makes me think the longevity of the flat panel display technology isn't so hot. Its OK on a laptop, you need to upagrade by the time the screen gets weak anyhow, but desktop monitors should last a lot longer.
This is the principle reason I haven't splurged for an Apple Cinema - I'd like to see one thats been in service for 3 years and compare it to a new one to see how it looks.