I had the same issue as many of you in this thread, but thankfully Apple did the right thing for me and agreed to repair my logic board and gpu free of charge.
I initially went to the apple store and was told that it was not the Nvidia issue because it would not even boot or pass the POST test (apple chime). I was offered the $310 + tax depot service to fix the logic board. I refused and left the store defeated. Then I started looking around the internet at threads like this one and the many others around the interwebs, and became determined that the faulty Nvidia GPU was my issue. Over the past few months I had been experiencing strange graphics glitches that I did not think anything about (lines on screen, shadows in bottom of screen).
My winning strategy was calling apple telephone support, telling the 1st tier support that I was affected by the NVidia issue, and then being connected to an Senior Apple Advisor. I told my story to the senior advisor about the recent graphics problems, and then how on one day I tried to wake my early 2008 mbp from sleep only to find it dead in its tracks. She was sympathetic and reluctant to admit that it could be the GPU, but rather that it was the logic board at fault. I explained to her how Apple could not possible]y rule out the faulty GPU as causing the logic board to short out and that the graphics glitches were extremely suspicious. After another 10 minutes of denial on her part she finally agreed to call the local apple store and see if they could "work something out for me" She ended up talking to a few other departments within applecare who decided that there was technically a possibility of the GPU being at fault, and that they only way they could determine if it was indeed the gpu was to open it up and inspect the logic board. This, coupled with the fact that I had purchased applecare warranty on my machine, convinced apple to fix the gpu (which basically means replace the logic board) free of charge since i was still within the 4 year nvidia quality program. I took it to my apple store today and they sent it to the depot for logic board replacement. Basically all is well in Macbook town! Hope my story helps or at least inspires all you struggling early 2008 mbp owners out there. Best of Luck!!