I noticed them in the Economist around 2010, and thought they were slick. Tons of software will autodetect "---" as an emdash so that works. Honestly, even if

I noticed them in the Economist around 2010, and thought they were slick. Tons of software will autodetect "---" as an emdash so that works. Honestly, even if it doesn't make it pretty I find stringing together a few hyphens does the trick in less formal settings.