Zope now provides site.zcml in its instance skel.

doc/CHANGES.txt

@@ -18,6 +18,20 @@ Zope Changes
 
     Restructuring
 
+      - Zope 2.10+ now includes site.zcml as part of its instance 
+        creation skel directory.  As a consequence Five now requires 
+        this file to exist in every instance.  If upgrading a site 
+        from Zope 2.9 to 2.10, you will need to copy site.zcml and 
+        package-includes/ from your installed Zope installation 
+        location (skel/etc/) into the etc/ directory of your upgraded 
+        instance.
+  
+        The rationale for requiring this new file is to bring Zope 2 
+        instances closer in consistency to Zope 3 instances.  It also 
+        eases use of Zope 3 coding techniques in Zope 2 and removes 
+        some confusion when trying to run pure Zope 3 applications on 
+        Zope 2.
+
       - Products.PageTemplates now uses the Zope 3 ZPT implementation
         in zope.pagetemplate.
 

skel/etc/site.zcml

+<configure xmlns="http://namespaces.zope.org/zope"
+	       xmlns:meta="http://namespaces.zope.org/meta"
+           xmlns:five="http://namespaces.zope.org/five">
+
+  <include package="Products.Five" />
+  <meta:redefinePermission from="zope2.Public" to="zope.Public" />
+
+
+  <!-- Load the meta -->
+
+  <include files="package-includes/*-meta.zcml" />
+  <five:loadProducts file="meta.zcml"/>
+
+
+  <!-- Load the configuration -->
+
+  <include files="package-includes/*-configure.zcml" />
+  <five:loadProducts />
+
+
+  <!-- Load the configuration overrides-->
+
+  <five:loadProductsOverrides />
+
+</configure>