Open source has always been dominated by men -- perhaps fifteen times more than computing in general. Over the years, various groups have been founded to change this focus, but it has only been in the last couple of years that the problem has been widely reported.
This documentation of the problem has created widespread denial. In its milder forms, the reaction ranges from claims that it doesn't matter to reluctance to admit that the community is less enlightened than most members like to believe. However, in its extreme form, the reaction is openly hostile, and includes declaration of male supremacy, threats, and hate mail.
The issue may have reached a new level with last week's creation of The Ada Initiative, a non-profit organization dedicated to encouraging women's participation in FOSS.
The Free software vs. Open Source debate is the flame war that never quite goes away its the one that regularly splits the community down the middle.
When "open source" was first coined thirteen years ago, the intention was to popularize a more business-friendly term than "free software." However, today the division is between those who emphasize the philosophical and political implications of free licenses (free software) and those who emphasize the enhanced quality of software with free licenses (open source).
The division isn't always so clear, of course. The more thoughtful open source advocates hold that quality applications are a means towards the personal freedom emphasized by free software. In addition, free software supporters vary from those who will never use proprietary software to those who will only do so reluctantly until an alternative is available.
However, at times -- for example, during the debate over the third version of the GNU General Public License -- the two viewpoints can become so distinct that supporters on both sides seem to forget that they are allies, and closer in viewpoint to each other than anybody else.
These aren't the only flame wars I could have mentioned -- not by any standard.
If I wanted to focus on operating systems, I might have mentioned Linux vs. Windows, or dredge up early history and talk about Linux vs. Minux (otherwise known as the Tannebaum-Torvalds debate, or the micro-kernel vs. macro-kernel debate).
I could mention popular distributions being pitted against each like Fedora and Ubuntu, or browsers like Mozilla and Chrome, or licenses such as the GNU General Public License and BSD-style licenses. The choices are as endless as the arguments themselves, and no doubt will only increase in the future.
For example, now that Debian ships with a free kernel, other distributions may find themselves under increasing pressure to do the same.
The playwright George Bernard Shaw once described England and the United States as "two countries divided by a common language." You could say much the same thing about the FOSS community -- at times, it seems like hundreds of users and developers divided by a common selection of software.