8GB works MacBook 5,1 (Late 2008) 2.0Ghz C2D
I can verify that 8GB RAM will work in a MacBook5,1 Aluminum Unibody Intel C2D 2.0Ghz running Snow Leopard 10.6.6. I just installed 2x4GB of Crucial DDR3 PC3-8500 204-Pin SODIMM RAM and have tested it by opening every program on my computer utilizing over 4GB of the RAM. I'll update later when I run some benchmarks on the RAM itself to use closer to 8GB. About this Mac, Activity Monitor, and iStat Pro show either 8GB or 7.75GB (due to the NVIDIA 9400m having 256MB shared RAM with the system).
If necessary I can provide screen shots, etc. Also, I got the RAM for 80$ off NewEgg (it was actually cheaper to buy 2 individual 4GB sticks from Crucial than to buy the identical sticks in a 2 pack).
8GB RAM + SSD is awesome. My computer feels faster and more responsive than my brother's Late 2010 13.3" MacBook Pro (OSx10.6.6 2.4 Ghz Intel C2D, 4GB DDR3 1066 RAM, NVIDIA 330m w/256MB Memory).