With the Macbook Air, Apple adopted an open-cell assembly, where panel makers only complete the cell part of the LCD module. They then ship the unfinished product to backlight unit makers to finish the backend part of LCD module assembly using panel modules 3 to 5mm thinner than the traditional procedure others use. Naturally, Acer, Asus, and Lenovo want in on this process.
The biggest problem with thin notebooks is their price tag. Apple's option is expensive, and so was Dell's Adamo XPS, even though it was quite an "engineering marvel." Hopefully, with more companies entering the fray, we'll see competition result in a good old price war that benefits all types of consumers.