Writing for readers in more than one language usually means one of two bad options: a separate WordPress install (and separate plugins, themes, and updates) per language, or a translation plugin bolted onto a site that was never built for it. FolioPress is neither — it's a single blog that natively speaks every language you configure.
Every post you write lives once, with a translation in each of your blog's languages. Add a language today, translate your existing posts on your own timeline, and every future post gets the same treatment automatically — no separate content trees to keep in sync.