Of course books with a broader appeal will outsell computer books. I'm not sure what you mean by a 'row' in a bookstore. I enjoy visiting my Big Bold Bookstore here in California. Ours has something like 500 linear feet of computer books. It's interesting how they have one section of titles mostly like "How morons can program visually in 42 days secretly revealed", and other sections with shelves full of good stuff. The good stuff overflows onto tables and displays. The other big bookstore in town (which is not really known for high-tech) has more expensive coffee but they only have the junk section, with maybe one or two shelves of good stuff.
It has varied over time, but I think the Perl book shelf space is at least 4:1 bigger than the Ruby. Ruby of course has a great growth rate, which is what gets many people excited. If anyone tells me about a really slick open source dynamic cross-platform language that creates sharp native-app GUIs and has good high speed numerical libraries, I'll want to try it. If it ever happens, I expect I'll learn all about it in my local bookstore soon after I first hear about it.
I'll pay the extra 30% to buy it there, because mostly I buy where I shop.