As far as I know, this is a pretty normal thing. I'm not trying to bash on Apple or anything, as I like their stuff, but I've heard that their keyboards mark the hell out of the screen on their notebooks.
Yeah that is a problem, you can simply change the trackpoint to the eraser head (not sure if you got it, but when I bought mines, they gave me 3 different trackpoint heads). i use tape to get it off. When you use scotch or transparent tape, you can really see the oil.
I work as a site tech for a local insurence agency. We have 45 A31 Thinkpads and I have had to change the screens on 3 from people closing the laptop and apply pressure to the back of the screen that the entire keyboard left its imprint on the screen. There isnt enough windex in the world to remove the marks that Ive seen. Personally I havent had any issues with it but I treat my laptop liks its my child