Well..
It sounds like the original poster wants a better quality camera, i assume he means camera module not lense. as lenses don't increase megapixels.

The lense and ccd are in same module, which is usually connected to the mainboard by a flex cable with a snap connector, and looking at the disassembly video of the n900 the module looks like that of the n95. If i ever open my n900 i'm quite willing to give it a go. (yes i know thats 5mp too but meh)

N8 camera module in n900 ? heh heh