They're very light and can only be seen when the screen is off and you're looking at it under a bright light. The PSP's screen is very sensitive and these scratches are pretty unavoidable, but they do nothing to hamper gameplay in any way. Like I said, you can't even seen them except for under a bright light.
I'll try and get pics up, but my digital camera is a piece of crap so they'll probably be too blurry...