What are the details?
As someone who manages people, I can see it causing dissension in the ranks. Everyone has their own perception of the job they do and even on a team of people at equal levels, there are people who clearly do more than others, whom I trust more with clients, and consequently deserve to get paid more, despite what the other people on the team think of themselves. If it requires open access to salaries, it will probably just depress salaries overall.
It doesn't require open access to salaries it just prohibits policies making discussing salaries a fire-able offense. If I even divulge how much I make to another person I can get fired for it.
Unfortunately for your expectations, nobody I've discussed salary with (I'm such a rebel) has run to our managers demanding higher compensation. It can, however, create tension if a) you actually have "favorites" or discriminatory spending or b) the coworkers are already antagonistic.
What these policies are really around for is to quell a source of worker/manager tension and so prevent unionization.
Edit: I should point out that a couple of people that I've discussed salaries with have gone to management to pursue higher wages. Not because they thought I was being given special treatment but because they realized how badly they had been getting fucked.
More Edit: And these weren't people who were bad performers, just that we had started off (at the same time) in different offices and they realized that the management of their office was being stingy as hell with cost-of-living and performance increases compared to other offices.
