A reminder to everyone that the National Labor Relations Act prohibits companies from firing employees for discussing their salaries:
There's the bigger problem with sharing your salary openly: raises.
My dad told me when I started working "Don't talk about your salary unless you don't want to see a raise again." It's not that absolute in practice. For many, raises are doled out yearly and are an average percentage with discretion to give some more and some less than the target. Even when well deserved, it's not easy to squeeze into the higher percentage but one way to make it a whole lot more difficult is to be revealed as someone who'll tell all the coworkers what they received. That'll almost certainly be on your bosses mind when it comes time for that decision and you might find yourself fighting to get an average raise since giving you the lower raise has the added benefit of making everyone else think they did better.
Share it on the Internet, openly, and now everyone in the company can know what you make. If you're paid over-average, your boss might even get a phone call asking "why?". That's just not a good place to be.
Interpersonal, HR related issues are usually very low on the list of things your manager enjoys. Assuming you're well known for publicly discussing salary, giving you an average raise and keeping you at the same salary might make you a little upset when you feel you deserve more (to which you might get a "my hands are tied" or "there wasn't room in the budget, this time"), but giving you a salary that eclipses your colleagues will make the rest of the team angry -- and probably a lot more angry than you'll get by just receiving the average. Unfortunately, the math ends up being not to your benefit.
Smart people make more money, then save it and then use the fact that they have 6 months expenses saved to leverage getting even more money.
I would suggest anyone attempting to claim NLRA protection actually read the document, particularly clauses like the exclusion of protection for supervisors discussing salaries.
I have access to VCS, bugbases, all the documents. We're a very metrics-oriented organization. And the one thing that defines where I stand with the company, I can't be trusted with.
I think if I didn't get a check every two weeks with the number on it, they wouldn't tell me how much I'm paid.