Patch for nvidia gfx driver (http://www.nvnews.net/vbulletin/showthread.php?t=62021) adapted for nvsound.
Created attachment 77348 [details, diff] gcc 4.1 fix w/o patch you'll get something like this: WARNING: //lib/modules/2.6.16-rc1/misc/nvsound.ko needs unknown symbol remap_page_range
It seems this patch also helps with newer kernels, where the unpatched version breaks, even w/o using gcc 4.1. So you probably want to include it in the ebuild.
*** Bug 129320 has been marked as a duplicate of this bug. ***
Forgot to close all this, nforce-audio is no more in portage.