The more interesting thing to me is not just that the base salaries were different, but that her personal bonuses were denied by her manager while her male coworker's bonuses were awarded — despite both of them being involved with the creation and distribution of the spreadsheet.
Regarding negotiation, I don't think companies really benefit from doing it. If they offer as much as they are willing to pay for your talent up-front, then you can adopt a take it or leave it attitude. The company will gain the benefit of increasing pay equality. Having pay equality is a step towards increasing diversity, and increased diversity will produce better products and companies.