If you have downloaded a font in the last ten years you probably have seen this.
I remember when I first learned about this sentence. I was in my grammar school's computer lab playing a typing tutor game (probably from MECC), and it had me type this phrase repeatedly. After the first dozen times, I asked the computer teacher what was up.
I think more interesting than this article are the self-enumerating pangrams described in the one linked to it.