nlowe [1] filed a deletion request for yarnpkg [2]: So it appears this **is** in [community]. I couldn't find it when I built the pkgbuild...perhaps my AUR Helper wasn't searching official repos as well for some reason.
[1] https://aur.archlinux.org/account/nlowe/ [2] https://aur.archlinux.org/pkgbase/yarnpkg/
