I don't understand why you'd want this...? To me, that would make everything on the screen extremely small, and it would be a pain for me as someone who does graphic/web design, in that, if I design a site and it takes up half my screen, it might not even fit on somebody else's screen. So it's hard for me to tell what the average user is seeing.
First of all, resolution independence is coming. Another thing is, I work within audio/video so I want more faders and longer timeline and I don't care if the physical size was smaller.
Somebody who does graphic design should be using his Cinema Display anyway. TN panels used in laptops only give 6 bits but colour is defined in 8 bits. Better to have an external S-IPS panel...