After upgrading to kernel 2.6.36 I don't have sound. Bug has been already reported to alsa-devel list. Patch is ready. Is it possible to have it earlier in gentoo-sources before will be publish officially? Take a look on this thread: http://www.spinics.net/lists/alsa-devel/msg39182.html
Released in gentoo-sources-2.6.36-r1.