The quick summary, for anyone who hasn't followed the story, is that Eich donated $1,000 to support California's Proposition 8 in 2008. Prop 8 has a single meaningful clause:
"Only marriage between a man and a woman is valid or recognized in California."
In other words, it was a ballot measure with a single purpose: To block gay people from getting married in the state of California.
While the news of Eich's donation had become public in 2012, his appointment as CEO of both the Mozilla Corporation and Foundation (the Foundation is a non-profit that owns the for-profit Corporation) brought the controversy to the fore.
Eich argued that personal beliefs didn't impact his ability to lead the Mozilla Foundation, which explicitly supports "equality for all." But he steadfastly refused to apologize for his actions or beliefs.
While the blog post that announced Eich's resignation said that Eich wasn't forced out and made his own decision, it's clear that the outrage of the community played a key role.
The broader question is what the controversy means.
One storyline is that Eich's ouster reflects the continuing and rapid change in attitudes towards LGBT individuals; remember, Prop 8 *passed* in 2008, and none other than future president Barack Obama declined to endorse marriage equality when asked about the topic. Today, a majority of Americans, including President Obama, support marriage equality, and full marriage equality in the United States is only a matter of time.
The opposing storyline is that Eich's ouster reflects political correctness run amok, and that forcing the co-founder of a company to resign because of his personal beliefs, rather than illegal action or malfeasance, sets a chilling precedent that few would want to see extended.
Whether you buy into the "political correctness" storyline depends on whether you consider Eich's support for Prop 8 a matter of politics or civil rights.
Most of us rightly feel uneasy about seeing anyone lose their job because of their politics. We believe in freedom of speech, and firing someone for their political beliefs seems morally wrong. I certainly wouldn't want someone firing me over my political beliefs (no matter how well I manage to cloak them in my public utterances!).
But Eich's continued opposition to marriage equality isn't a matter of politics; it's a matter of civil rights.
Prop 8 was designed to deny civil rights to a specific group of people. And not just any civil right, but the right to marry whom we choose, which has to be one of the most fundamental and personal of rights.
Until 1967, interracial marriage was illegal in the American South, as far North as West Virginia, and as far West as Texas. That means that less than 50 years ago, my wife and I would not have been permitted to marry in roughly 1/3 of our country. As recently as 1958, a Gallup poll found that 96% of white Americans disapproved of interracial marriage. I've mentioned these facts to my kids, who find them, frankly, unbelievable (a fact that I'm quite happy about).
Imagine if Eich had donated to a group that was dedicated to banning interracial marriage, or to bringing back segregated schools? Would there be any controversy over his resignation? Would anyone argue that calling for the ouster of a segregationist would be "political correctness run amok?"
Marriage equality is a matter of civil rights, and impacts all of us. Marriage is a fundamental human right, and should not be denied to any couple, regardless of their parentage, wealth, or sexual orientation.
Brendan Eich was given the opportunity to apologize for his actions, but refused to do so. I respect his decision to stay true to his beliefs, even when it would be convenient to lie. But his beliefs are fundamentally wrong, and his resignation was the right outcome for Mozilla. A company that espouses equality for all cannot be led by a man who continues to believe the opposite.