The session interface is new in 0.8, not 0.7

docs/api.rst

@@ -198,7 +198,7 @@ To access the current session you can use the :class:`session` object:
 Session Interface
 -----------------
 
-.. versionadded:: 0.7
+.. versionadded:: 0.8
 
 The session interface provides a simple way to replace the session
 implementation that Flask is using.

flask/sessions.py

@@ -89,7 +89,7 @@ class SessionInterface(object):
         app = Flask(__name__)
         app.session_interface = MySessionInterface()
 
-    .. versionadded:: 0.7
+    .. versionadded:: 0.8
     """
 
     #: :meth:`make_null_session` will look here for the class that should