Lots of CEOs' salaries are public, but that doesn't stop people from resenting them for making so damn much. It's really hard for people to accept that someone is 3X or 5X or 100X more valuable than they are--either way, it's not a positive thought. I think more important than exposing salary numbers is being transparent about why those numbers are the way they are. Having the company tell me that Bill makes twice as much as me, by itself, might actually make things worse (especially if I don't think Bill deserves it), but knowing that he makes twice as much because he is highly specialized in a specific thing that the company really needs is useful because it gives me a hint as to how I can reach that level.

But aren't most salary discrepancies because you are a better negotiator than someone? Or what if the reason is that you are getting offers from other companies and so your company is giving you a higher salary to keep you around? The company wouldn't like to tell THAT is why they are paying you more, because then everyone would be "pay us more or we leave"

I don't think requiring as part of your employment that the whole world know your salary is a good thing in the private sector. But no one is forcing anyone to work at your company, although how it affects people that were there before this decision, to me is a bit questionable.