It hurts your morale in the short term, but it should give you the impetus you need to a. work harder b. negotiate harder when it comes to that yearly performance review and/or possibly c. leave if you feel you're being underpaid and the company isn't willing to pay you what you think you're worth.

I don't think full salary disclosure will ever happen, but I'm just saying, it wouldn't be bad if it did. I for one would just like to know, for example, what a iphone/ipad developer makes on average (then a high and low end) in ... say ... Austin Tx vs New York or something like that.