Well... Just came from the apple service and they gave me my MBP. It's not the screen's backlight.... Is the screen perse... The part# to be replace is 661-4346: Display Clamshell, 17" matte (AG).
Bring it to apple themselves if there is one near you. See if they would replace it under the 8600GT defect.
If Apple doesn't warranty, you can always use the laptop in clamshell mode if repairs are too $$$. Still a shame though.
This is a MIRACLE!!!!...
I turned my computer now and the screen came to life...