Raymond: We made our biggest misstep back around 1985, by letting our advocacy function get almost completely captured by the Free Software Foundation. On a purely technical level, open source could have become an effective movement any time after inexpensive 32-bit PCs became available around 1987. As it was, we lost 10 years because our theory was weak and politically tainted, our community fragmented, and our propaganda ludicrously inept.
To be fair, neither I nor anybody else wanted the advocacy job at the time. But it's notable that open source didn't break out of its hardcore-geek ghetto until Linus Torvalds and I found a better story to tell about it after 1997. Did you know that the Mayans invented the wheel but only used it for children's toys? Narratives really matter; open source wasn't the first technology to languish at the margins because it hadn't found the right generative myth yet, and it's unlikely to be the last.
CEO and co-founder
Rosenberg: There was no other way for open source to progress without trial and error related to both development and business. The biggest business misstep is probably the obsessive focus on licensing, which, while important, distracted people for way too long.
There are too many lessons learned to count, so I would say that open source projects and companies should have been much more aggressive at proving use cases in mission-critical environments. This has been going on for quite some time but has only started to get noticed in the last year or so.
Soltero:I'd argue the biggest lesson has been and will remain the "desktop issue." People jumped on Linux as a potential desktop replacement very early on, and the debate continues to this day. Meanwhile, the operating system and the associated infrastructure tools such as Apache, PHP, etc., continue to enjoy explosive growth and disruption on the server side. I know there are many who believe that Windows and even Mac OS X are bad because they're not open source. That might be true, but one cannot argue that the user experience for both of these operating systems blows away anything you'd get out of Linux (at least today). The lesson here is that open source can deliver more immediate, tangible benefits in certain areas than in others, and the market is smart enough to figure that out. We'll get a good Linux desktop one day, I just don't see it happening any time soon, and I don't know that that's the right priority given where desktop computing is headed.