Postscript is still used as an intermediate document format, since it is a fully fledged programming language allowing you to compute graphics, which PDF doesn't. PDF shows just the result (after some conversions, sometimes called "Distillation") of the computation Postscript is able to do.

Is PostScript widely used nowadays?

Although postscript will celebrate its 30th anniversary in 2014, it's still the predominant language for high-end printers and shows no signs of being replaced.

Does anyone use PostScript?

The postscript is indeed of limited use, but it might still be useful when one has something else to say, but doesn't want to compose the email all over again. People still do compose letters from time to time, and send them on paper. ... P.S., It also might be useful if one is mimicking an old-style letter format.