I noticed earlier today that although the nouveau kernel module is installed into the directory for the configured kernel, the makefile detects and builds against the running kernel. In my case this meant that a module built against gentoo-sources-2.6.30-r3 was installed into the module directory for gentoo-sources-2.6.30-r4 which isn't a huge problem, but I can see things breaking unexpectedly if the kernel versions are more different. This occurs when updating the kernel and rebuilding the module before rebooting into the new kernel.
Created attachment 199797 [details, diff] Patch which updates the ebuild to pass the correct directory to make
That was observant of you to notice in a case where it didn't actually break anything. Thanks for submitting your patch, assigning to x11 team.
This is now fixed in the x11 overlay.
@Chi-Thanh, please do close bugs when you've fixed them :) (unless maybe bugzilla doesn't let you do that?) Closing fixed then. Thanks