I think what it comes down to is that there would be too many form-factor
standards with laptops. In addition, you would need to have the screen
integrated into the case with all of these different sizes. The way that
dell and gateway and Sony mount their motherboards, hard drives, and other
components differs, even among laptops of similar size.
The point I guess I am trying to make, is that once you get so small, you
would see something like a small form factor PC, where the motherboard comes
with, and is designed only for that specific case, pushing prices up. It
doesn't really cost that much more, per laptop, to have someone slide in a
hard drive, stick of ram (sometimes even this is built into the
motherboard), and cpu.
Having one standard for a specific size would limit creativity, although it
would be nice for homebuilders. Whitebox notebooks, therefore, where you
add your own ram and hard drive, seem to be the closest thing to building
your own notebook that we'll have for a while. There are, as far as I know,
no plans for laptop case standards. If we had the standards, though, it
would mean being able to build a laptop quite easily, but just not a cutting
edge laptop.
Dave