[notacoward]

It has been around in industry for at least twenty years. Facebook is a bit unusual in using it as an actual job title, but it's by no means new. I remember talking about how DEC had a healthy IC track separate from going into management, and DEC hasn't even existed as a separate company since 1998.

[mst]

It's certainly regularly used but of course 'regularly' and 'common enough you can assume your audience already knows it' aren't necessarily the same thing in practice, usually at the most inconvenient possible moment.