since 2.6.25 the proprietary nvidia drivers <= 169.12 do not work any more.
there is already driver version 173.08 available from nvidia, although it is marked beta.
i created a ebuild in my personal overlay for 173.08 by just renaming the one from 169.12. the driver compiles and works as expected (at least on x86).
please create a ~arch ebuild and add it to the portage tree.
*** This bug has been marked as a duplicate of bug 218178 ***