My father's macbook which is just three months old is a goner. It refused to boot Tuesday last week. You get nothing but a black screen when you press the power button (even though the power LED is lit). Apparently this is a known issue. There are some variations of it as well. Some users have reported that the screen goes gray, others have reported flickering lines as well.
The usually suggested remedies like pressing certain key combinations on boot (Command+alt+P+R) doesn't do anything. Booting from a DVD does not work either. Taking out the battery and keeping the power button pressed for 5 seconds for a hard reset doesn't resolve the issue either. You still get nothing more than a blank scree and now the DVD is stuck in the drive and will not come out.
More drastic suggestions include replacing the RAM. Since I have a nearly identical Macbook, i I tried that as well. Still no dice. The battery was also replaced, but the black screen just refuses to go away. So finally took the darned thing to the agents for repairs. That's a week ago. They are still dragging their feet.