See URL for the release announcement
BTW upstream dropped tar.bz releases. They use tar.xz now.
copying zsh-5.0.8.ebuild to zsh-5.1.ebuild and updating the SRC_URI works fine.
Created attachment 411310 [details] zsh-5.1.ebuild if any
zsh-5.1.1 release announcement: http://www.zsh.org/mla/users/2015/msg00880.html @maintainers: If you are too busy with other things, I'd love to add myself to metadata.xml as maintainer as I am using zsh on all my non-root user accounts.
Added to the tree.