Farhad Manjoo, in Slate, delivers a spirited attack on double-spacers like me. Apparently the intersentence double space is irrational and unbeautiful. My readers mostly disagree, and more importantly, so does LaTeX. This argument reminds me of books I used to read as a kid about the forthcoming rationalization of English spelling. The inventor of the Dewey Decimal System, Melville Dewey — excuse me, Melvil Dui — was a big player here. Anyway, it didn’t happen. Our lumpy, irrational language, with its silent gh and its intersentence lacunae, trundles on its own track.
Quomodocumque 
I too will retain my double spaces…
The history in that piece was so bizarre: I’m a double space user exactly because of 1980s computer technology, not in spite of it! (Well, arguably TeX and Emacs are 1970’s computer technology, but I didn’t start using them until the 80’s.) And I really don’t know where “monospaced fonts went out in the 1970s” is coming from – I’ll accept that I’m idiosyncratic in my current usage of them (though not abnormally so, given that I’m a programmer), but in the 1970s??
Of course, single-spacers have an inherent advantage… if multiple people are working on the same document, the search-and-replace to convert the whole document from double to single can be automatic, while the s&r to go from single to double requires human verification.
Having just had to search-and-replace an entire document to remove double-spaces in order to comply with a journal style guide, I can say with confidence that there’s no way I can break myself of the double-spacing habit.
Deweys: do you know John Ashbery’s poem in which Admiral Dewey and the Dewey Decimal guy sort of meld, or merge? It’s straight-up humor compared to most of what he’s done, and very funny.
Spaces: I learned to put just one space between each sentence when I was writing for Let’s Go, which cares about character counts (or at least they did). I’m not surprised that lots of smart people double space, but I am surprised that Jenny does.