She created an internal spreadsheet allowing Googlers to add their salary information.

Lots of people helped tweak the sheet adding data visualizations, comparisons, etc.

Google management told her they didn't like it, she pointed out that you can't be fired for sharing salary information.

Lots of colleagues were giving her "peer bonuses" for setting this up, but her manager kept blocking them, something which is apparently unheard of to the point that most people didn't know they could be blocked.

By the time she left, 5% of staff were apparently using the sheet.

Even more TLDR: Nothing particularly happened except that Google showed they dislike colleagues talking about salaries.

TL;DR - Erica Joy created a spreadsheet of salaries, it got shared internally at Google, apparently about 5% of total workforce filled it in.

Google has some sort of Peer Bonus scheme, Erica got lots of them but management decided to deny pretty much all of them.

She left google.

Author created a spreadsheet with her salary/few other salaries of coworkers on it, posts it to google internal social network, 5% of workers fill it out, people start asking for better salaries, managers mad, her peer bonuses (coworker endorsements that net you a small bonus) get denied, everyone mad, she left(?)

ts; dr...

TL;DR - Google operates in a parallel universe called "California", where employees can share each other's salaries on a company-wide shared spreadsheet without getting fired.

Not only did Google NOT fire anybody for it, they haven't even removed the spreadsheet from their own internal network. They simply refused to approve some $150 "peer-recognition" bonuses, meant to reward the employee for creating the spreadsheet. THAT is apparently enough to engage some kind of weird quasi-SJW outrage. As opposed to the real world, where everyone involved would be fired and given a negative reference for the rest of their career.