Mine

##Example.py##
import dbus
import dbus.service

DBUS_NAME = 'org.foo.bar'
DBUS_OBJECT = '/org/foo/bar'
DBUS_INTERFACE = 'org.foo.bar'

class Example(dbus.service.Object):
        def __init__(self,bus_name):
                dbus.service.Object.__init__(self,bus_name,DBUS_OBJECT)

        #@dbus.service.signal(DBUS_INTERFACE, signature='s')
        @dbus.service.signal(DBUS_INTERFACE)
        def SampleNotify(self, name):
                print "here SampleNotify!"
                return "SampleNotifyReturn"

## server.py ##
#!/usr/bin/python

import gobject
import dbus
import dbus.service
from Example import *

DBUS_NAME = 'org.foo.bar'
DBUS_OBJECT = '/org/foo/bar'
DBUS_INTERFACE = 'org.foo.bar'

name = dbus.service.BusName(DBUS_NAME,bus=dbus.SessionBus())
obj = Example(name)

loop = gobject.MainLoop()
print "listening..."
loop.run()


## client.py ##
#!/usr/bin/python

import dbus
DBUS_NAME = 'org.foo.bar'
DBUS_OBJECT = '/org/foo/bar'
DBUS_INTERFACE = 'org.foo.bar'
bus = dbus.SessionBus()
notify_obj = bus.get_object(DBUS_NAME,DBUS_OBJECT)
sender = dbus.Interface(notify_obj,DBUS_INTERFACE)
print sender.SampleNotify("sent from client")

## output of client.py ##
Introspect error: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.

## dbus-monitor output ##
signal sender=org.freedesktop.DBus -> dest=(null destination) path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameOwnerChanged
   string ":1.44"
   string ""
   string ":1.44"
method call sender=:1.44 -> dest=org.freedesktop.DBus path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=Hello
signal sender=org.freedesktop.DBus -> dest=(null destination) path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameOwnerChanged
   string "org.foo.bar"
   string ""
   string ":1.44"
method call sender=:1.44 -> dest=org.freedesktop.DBus path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=RequestName
   string "org.foo.bar"
   uint32 0
signal sender=org.freedesktop.DBus -> dest=(null destination) path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameOwnerChanged
   string ":1.45"
   string ""
   string ":1.45"
method call sender=:1.45 -> dest=org.freedesktop.DBus path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=Hello
method call sender=:1.45 -> dest=org.foo.bar path=/org/foo/bar; interface=org.freedesktop.DBus.Introspectable; member=Introspect
method call sender=:1.45 -> dest=org.foo.bar path=/org/foo/bar; interface=org.foo.bar; member=SampleNotify
   string "sent from client"