Policy Regarding Employee Pay Information

Invariably our staff "spills" to each other their pay rates. Feelings get hurt, people are angry, etc. Does anyone have a written policy about this? Or other guidance about dealing with this?
Comments
>"...in this case"<
I take it you found this to be a first!?!
No, VPHR, I enjoy all of your responses. When I said, "...in this case" I meant in regards to the posters issue.