Ban on Employee Conversation on the Job

Restaurants are about service. When employees are too chatty amongst themselves, they are distracted and unable to provide the undivided attention customers seek. Customers look over at the talking waitstaff and somehow feel cheated and ignored, and resent being unwilling voyeurs to the conversation. In fine dining and upscale establishments, “silent service” is expected.
On the other hand, promoting a team environment between staff members can enhance a friendly, inviting ambience for both patrons and workers. I read a blog chain where a waitstaff member asked if customers prefer a chatty waitress or one who just delivers the food. The responses were interesting. In the end, patrons seemed to like waitresses with a friendly sociable approach, and a sense of humor, but disliked full conversations with waitstaff. Customers are there to enjoy the evening and conversation of their dinner companions. The expectation is good service by attentive waitstaff, but not an extra person at the dinner table.
I am interested in what others think. Should restaurant owners and managers discourage chit chat amongst the staff? What will this do to employee morale?