Sometimes ignorance is leverage. A few years back, when I made the switch from one media company to another, it was precisely the lack of transparency about my salary that allowed me to more than double my salary in the process.
I happen to be good at job interviews, and at the end of a particularly impressive one I threw out a very high number, thinking to myself that the worst that could happen would be a "no." They said yes. This would have been much harder to pull off had my prior salary been published. Ever since then, one of the pieces of advice I give to women who are negotiating their salary is to always ask for as much money as they can say out loud without laughing.
One young woman I spoke with, who currently works in the government, voiced concern about having the money conversation be so open. "I think it does take away a certain leverage," she says of the fact any new employer could, if they wanted to, Google her previous salary. "I will try to avoid as much as possible [revealing that it's public]. I think when I move to my next job, I will try to withhold."