Same symtoms on my laptop also, Network Manager do not connect to wireless when using dbus-1.2.1-5 or dbus-1.2.8-1. As Jon Westgate said, reverting dbus back to 1.2.1-4 solves the issue.
I'm running Debian GNU/Linux 5.0 (lenny), with kernel 2.6.26-1-686, network-manager 0.7.0-1, and network-manager-kde 1:0.7~~svn908338-1, and iwl3945 When running dbus-1.2.1-5, i got the following messages in /var/log/daemon.log: --- NetworkManager: <WARN> connection_get_settings_cb(): Couldn't retrieve connection settings: Rejected send message, 1 matched rules; type="method_call", sender=":1.8" (uid=0 pid=3213 comm="/usr/sbin/NetworkManager --pid-file /var/run/Netwo") interface="org.freedesktop.NetworkManagerSettings.Connection" member="GetSettings" error name="(unset)" requested_reply=0 destination="org.freedesktop.NetworkManagerUserSettings" (uid=1000 pid=3583 comm="/usr/bin/knetworkmanager ")). NetworkManager: <WARN> wait_for_connection_expired(): Connection (2) /org/freedesktop/NetworkManagerSettings/Connection/1 failed to activate (timeout): (0) Connection was not provided by any settings service --- and for dbus-1.2.8-1: --- NetworkManager: <WARN> connection_get_settings_cb(): Couldn't retrieve connection settings: A security policy in place prevents this sender from sending this message to this recipient, see message bus configuration file (rejected message had interface "org.freedesktop.NetworkManagerSettings.Connection" member "GetSettings" error name "(unset)" destination "org.freedesktop.NetworkManagerUserSettings"). --- Greetings, Juan Traverso Viagas