Jonathan answered that question directly in his blog: "My response was simple. "Steve, I was just watching your last presentation, and Keynote looks identical

Jonathan answered that question directly in his blog: "My response was simple. "Steve, I was just watching your last presentation, and Keynote looks identical to Concurrence – do you own that IP?" Concurrence was a presentation product built by Lighthouse Design, a company I’d help to found and which Sun acquired in 1996. [...] Steve had used Concurrence for years, and as Apple built their own presentation tool, it was obvious where they’d found inspiration." (emphasis mine)