You may have some employees who wish to keep this information for themselves either because they feel they can gain from it financially or for other reasons.
That is why it is so important to keep them motivated. This is also a reason why it is important to understand your employees and the business environment. In order to choose your method to motivate them, you really need to understand them.
Giving them incentives is also important. Again, this will all depend on the employees and work environment. What do they value? What will make them happy and keep them motivated?
Of course, those are just suggestions. The method that you choose will depend on what is best for your company. Also, you may want to use a few different methods. This works especially if your company is large. This means you will satisfy different personality types. Those who like gifts will be happy with the gift certificates, those who like to be praised in front of others will also be happy, etc.