Comment 10 for bug 356152

The text in software-properties is misleading, that is obviously bad. If you think the auto launching is not working, you can test it with (in a terminal):
$ NO_FAKE_STAT=1 faketime '10 days' update-notifier
(you will need the faketime package for this to work).

You need to reset the launch time afterward with:
$ gconftool --unset /apps/update-manager/launch_time
to ensure that its not recorded as launched 10 days in the future.

There is also "update-notifier --debug-updates" to check why it thinks it does not need to auto-launch.