Richard Poynder has published "The Open Access Interviews: John Willinsky" in Open and Shut?.
Here's an excerpt:
I was fortunate enough to draw together a wonderful team, led by the Associate University Librarian Brian Owen and technical wonder Alec Smecher at Simon Fraser University Library, who, through the research and development funds we were able to raise, created open source systems for scholarly workflow management and publishing. Together, we created Open Journal Systems (OJS) beginning in 2002, to answer the question of what will it cost to put a journal online. . . .
Over the course of the next decade, the use of OJS has spread across the globe to the point where—with 8,000 journals actively using it in 2013—we now feel a considerable responsibility at PKP for ensuring that this system provides a high-quality editorial workflow and publishing environment, and all the more so with roughly half of those journals in the Global South.
So in terms of your question on what PKP has developed into, I would say that it has become primarily but not entirely an open source software development and community support project in a global scale.