Hi,
I've the same problem of the NVidia Geforce 8600M GT which is not found by the system any more after a sleep. Everything else works fine, because I can run it from remote display.
I've reinstalled the system, repeated PRAM and SMC reset a few times, without success
A similar problem was solved a few months ago on this MBP by SMC reset (before the end of the 2 years of warranty provided by applestore), but now it does not power up the framebuffer (it is now 2 years + 1 month old, and without AppleCare). So it is not late to notify the problem, according to the european law, but Apple refuse to consider this problem as a defect
The support center has tested (probably from usb) the system, and Nvidia seems to work fine, but they said the logic board is broken. I'm writing connected to the broken MBP from another MBP, so everything works except the start of NVidia
I think this is a defect of these machines, but when I asked to open a request to Apple for this defect (Consumer Law repair Validation), they said that this is not a manufacturing problem that (latently) existed from the time of delivery, so ....I'm simply out of warranty
I'm also not included in the program which extend the warranty for NVidia Geforce 8600M GT problems, because the framebuffer can complete the NVidia test successfully.
I think this is not a complete test, because they do not to verify the connection between logic board and this broken set of framebuffers.
The apple authorized center asked too much money to fix it (870 euro + tax), so it's now, broken, at home
I can add that the previous powerpc computers where much better (still perfect after 6 years!)
I hope unibody is really unbreakable, otherwise Apple will loose a lot of customers