It's not immediately clear from reading this what this means for ACM books, both older ones and new ones. I'm a fan of a lot of their older books, such as the Turing Award Lecture anthology they published in the early 1990s. I'm also interested in some of the newer books they've published in the last several years (The tributes to Dijkstra and Hoare especially stand out). I really hope these are included as well.
I am willing to admit that I find matrix multiplication ugly, as well as non-intuitive. But, I am also willing to admit that my finding it ugly is likely a result of my relative mathematical immaturity (despite my BS in math).