These days, employees are getting braver about discussing their pay. Part of the reason is that the National Labor Relations Board has done a good job publicizing its stance that discussing pay is concerted activity protected by law.
Be prepared for the inevitable lawsuits with solid reasons for all pay decisions.
Recent case: Doris Keeton, who is black, sued her employer, alleging she was paid less than her two white co-workers. But the company showed that it used market factors to determine starting pay.
Plus, the salaries were very close, with Keeton earning a mere $150 less after the most recent salary increases. That was enough to get her case tossed. (Keeton v. Morningstar, No. 11-2298, 7th Cir., 2012)