I wasn't able to get audacity 1.0.0 or 1.1.0 to work. I downloaded the latest version of the source from sourceforge (http://prdownloads.sourceforge.net/audacity/audacity-src-1.1.1-3.tgz?download) and got it to work. I needed to apply the mono-mp3-export patch by Paolo Patruno (http://article.gmane.org/gmane.comp.audio.audacity.devel/1011/match=mono+mp3+export) . All of the files for this ebuild are available at http://rekl.yi.org/gentoo_patches/
Created attachment 7328 [details] audacity-1.1.1 ebuild
Created attachment 7329 [details] patch to audacity-1.1.1 for mono mp3 export fixes
Created attachment 7330 [details] digest for audacity-1.1.1
audacity-1.1.1 has been added to portage and is marked stable. Thanks for the heads up on the patch.