Similarities are visible in every step of the way: with operative verbs like to publish, to bump up a version, to add another page etc. Book writers thrive on masterful use of grammatical constructs and subtle nuances of a human language (like English). The pursuit is to punch with an impeccable prose.
Software writers too thrive exactly on the same parapet of expertise, but only in a computer language. Given that higher level computer languages vie for human-ness, one can only imagine if a convergance of trades has already occurred or is imminent. I'd think the former but there is no way to know for sure.
Similarities don't end with pursuit of authors alone. Both books and apps have a design need. A need for layout and thoughtful typography to engage and wow the consumer. Thankfully, design is considered separate from content in the world of books too, so much of our app design processes are also valid for book design.