Index: trac/ticket/api.py
===================================================================
--- trac/ticket/api.py	(revision 3464)
+++ trac/ticket/api.py	(working copy)
@@ -68,6 +68,10 @@
         [wiki:TracTickets#AssigntoasDropDownList AssignToAsDropDownList]
         (''since 0.9'').""")
 
+    show_keywords = BoolOption('ticket', 'show_keywords', 'true',
+        """Show the keywords field for tickets.
+        (''since 0.10'').""")
+
     # Public API
 
     def get_available_actions(self, ticket, perm_):
@@ -136,6 +140,8 @@
 
         # Advanced text fields
         for name in ('keywords', 'cc', ):
+            if name == 'keywords' and not self.show_keywords:
+                continue
             field = {'name': name, 'type': 'text', 'label': name.title()}
             fields.append(field)