You'll need to do reset-gaia to give the template app the good permissions (or edit permissions.sqlite).

default.diff

 test_apps/template/index.html      | 16 ++++++++++++++++
 test_apps/template/manifest.webapp |  6 +++++-
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/test_apps/template/index.html b/test_apps/template/index.html
index 4611ccd..baca876 100644
--- a/test_apps/template/index.html
+++ b/test_apps/template/index.html
@@ -16,6 +16,22 @@
     </style>
 
     <script>
+    var mContact = {'familyName': 'Prout'};
+    mContact.tel = [
+        {'value': '+33 6 99 99 99 99'}
+    ];
+
+    var contact = new mozContact();
+    contact.init(mContact);
+    var saving = navigator.mozContacts.save(contact);
+
+    saving.onsuccess = function() {
+        console.log( 'yahoo!');
+    };
+
+    saving.onerror = function() {
+        console.log( 'boo :(');
+    }
     </script>
   </head>
 
diff --git a/test_apps/template/manifest.webapp b/test_apps/template/manifest.webapp
index 69119ac..958886c 100644
--- a/test_apps/template/manifest.webapp
+++ b/test_apps/template/manifest.webapp
@@ -55,5 +55,9 @@
   "default_locale": "en-US",
   "icons": {
     "128": "/style/icons/Blank.png"
+  },
+  "type": "certified",
+  "permissions": {
+    "contacts":{ "access": "readwrite" }
   }
-}
\ No newline at end of file
+}