As I wrote recently we, the product managers, can trace our beginnings to the 1930's memo that instituted the role of a brand manager at Procter & Gamble. While the product oriented organization was quickly adopted by other consumer-oriented companies, it's relatively new phenomenon in computer industry. Namely, the big challenge with first computers were not selling them but making them, therefore functional organization made much more sense. And once the companies such as IBM mastered the process of building computers they sold their computers in small quantities to a handful of big companies, which made organization by key accounts more aligned with the business needs of those times.
Personal computer industry that got its start in the 1970's recruited its stuff mostly form established computer companies such as Digital and HP. Consequently also organization of early PC companies were modeled after the computing giants of that time with little customer focus (unless the engineers themselves were the customers of the product, too). The role of a product manager was introduced to PC industry only in the early eighties by Scott Cook, founder of Intuit, who was previously a brand manager at Procter & Gamble. While I couldn't find any literature supporting a claim that Intuit has direct influence on later development of a product manager role in computer industry, I find it very interesting that Bill Campbell served as CEO of Intuit from 1994 to 1998, that is, the same time he served as a board member of Netscape and wielded huge influence over young Ben Horowitz who can be rightly considered a father of modern product management in computer industry.