This is a proof of concept app for dealing with basic I18n needs in ember that I plan to extract into an addon.
There is an existing library out called ember-i18n, but it supports much more than the simple use cases I need. It also does not work with Ember >= 1.9 and renders out script metamorph tags.
format.js also looks promising, but it also does quite a bit more than I need. There is some overlap with the I18n built into momentjs, which I use on all my ember projects already anyway.