Ok...I have an update that may be of some interest. I decided to give my WhiteBook a wipe down this morning before I headed off to uni for the day. The screen in particular was looking a bit dusty/dirty so I used my iKlear polishing system as usual...But this time, just to see how it worked, I used one of the little 2-step disposable wipes packets from iKlear (comes with the deluxe package).
I had noticed since having received this (3rd) macbook that there was an odd smudge mark in the bottom left corner of my screen, about the size of a silver dollar and, upon closer inspection, what seemed to be a fingerprint in the unknown substance. I went at it with my polishing cloth (which is white, by the way...) and when I was done polishing that area, I noticed that the cloth had turned a yellow color.
Now to the point...Could this yellow discoloration be coming from some sort of adhesive, grease, or other manufacturing substance used to assemble these things? I know for a fact this did not come from me, as I noticed the smudge almost immediately upon opening the MB for the first time...Anyone else seen this before?
It has since been cleaned from the screen, although I must say that it took a lot of spraying, wiping, spraying, wiping, spraying, wiping to get it to budge. It seemed to initially cover my entire screen with a hazy film.

Now the screen is back to normal, shiny and perfect as can be...I haven't seen any discoloration in this one yet, but I'll keep you posted.
EDIT #1: Just found
this while surfing the web for polycarbonate/plastic cleaners...Maybe it would work? It says "For home or industrial use, NOVUS has formulated a complete system to restore scratched, faded or discolored plastic materials." BTW, has anyone gone out on a limb and actually try any, more industrial-strength cleaning agents?
EDIT #2: After a bit more searching, it seems as if polycarbonate (if that's really what this is made of) is pretty resistant to discoloration due to chemicals/reagents; however, it still suffers from UV yellowing, as it's called. Interestingly enough, as the sustained temperature of the polycarbonate during UV exposure increases, so does the rate at which the material "yellows." MacBook w/heat issues+UV exposure = discoloration? For the people who are suffering from discoloration, what are your idle and loaded temperatures?