dbus python working? "Unable to determine the address of the message bus"

I've got dbus 0.20 from debian and I'm trying out the python bindings.   
I grabbed the examples from 
http://dri.freedesktop.org/cgi-bin/cvsweb/dbus/dbus/python/examples/ but 
when I run example-server.py I get:
   Traceback (most recent call last):
     File "./dbus-server.py", line 17, in ?
       service = dbus.Service("org.designfu.SampleService")
     File "/usr/lib/python2.3/site-packages/dbus.py", line 183, in __init__
       self._bus = Bus()
     File "/usr/lib/python2.3/site-packages/dbus.py", line 57, in __init__
       self._connection = dbus_bindings.bus_get(bus_type)
     File "/build/dstone/dbus-0.20/python/dbus_bindings.pyx", line
   1155, in dbus_bindings.bus_get
   dbus.DBusException: Unable to determine the address of the message bus


I have "dbus-daemon-1 --session" running, btw

Are these examples out of date?  The cvs page says they are 3 months old.