It still does not work on my machine (Dell X1). Here is the logfile with my comments inbetween:

# Closing the lid...

[hal_device_condition_cb] gpm-button.c:393 (11:09:54):	 condition=ButtonPressed, details=switch-videomode
[emit_button_pressed] gpm-button.c:337 (11:09:54):	 emitting button-pressed : switch-videomode
[button_pressed_cb] gpm-manager.c:999 (11:09:54):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-srv-screensaver.c:167 (11:09:54):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-backlight.c:515 (11:09:54):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-info.c:698 (11:09:54):	 Button press event type=switch-videomode
[hal_device_property_modified_cb] gpm-button.c:363 (11:09:54):	 key=button.state.value, added=0, removed=0, finally=1
[hal_device_property_modified_cb] gpm-button.c:372 (11:09:54):	 state of a button has changed : /org/freedesktop/Hal/devices/computer_logicaldev_input_2, button.state.value
[emit_button_pressed] gpm-button.c:337 (11:09:55):	 emitting button-pressed : lid-down
[button_pressed_cb] gpm-manager.c:999 (11:09:55):	 Button press event type=lid-down
[lid_button_pressed] gpm-manager.c:952 (11:09:55):	 Performing AC policy
[gpm_inhibit_has_inhibit] gpm-inhibit.c:336 (11:09:55):	 Valid as no inhibitors
[manager_policy_do] gpm-manager.c:470 (11:09:55):	 policy: /apps/gnome-power-manager/buttons/lid_ac
[gpm_control_get_lock_policy] gpm-control.c:389 (11:09:55):	 Using custom locking settings (0)
[button_pressed_cb] gpm-srv-screensaver.c:167 (11:09:56):	 Button press event type=lid-down
[gpm_screensaver_add_throttle] gpm-screensaver.c:318 (11:09:56):	 adding throttle reason: 'Laptop lid is closed': id 96633217
[button_pressed_cb] gpm-backlight.c:515 (11:09:56):	 Button press event type=lid-down
[button_pressed_cb] gpm-info.c:698 (11:09:56):	 Button press event type=lid-down
[gpm_info_event_log] gpm-info.c:594 (11:09:56):	 Adding 8 to the event log
[button_pressed_cb] gpm-info.c:704 (11:09:56):	 lid button CLOSED
[hal_device_condition_cb] gpm-button.c:393 (11:09:56):	 condition=ButtonPressed, details=lid
[emit_button_pressed] gpm-button.c:314 (11:09:56):	 ignoring duplicate lid event
[hal_device_condition_cb] gpm-button.c:393 (11:09:56):	 condition=ButtonPressed, details=switch-videomode
[emit_button_pressed] gpm-button.c:337 (11:09:56):	 emitting button-pressed : switch-videomode
[button_pressed_cb] gpm-manager.c:999 (11:09:56):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-srv-screensaver.c:167 (11:09:56):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-backlight.c:515 (11:09:56):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-info.c:698 (11:09:56):	 Button press event type=switch-videomode
[dpms_mode_changed_cb] gpm-srv-screensaver.c:196 (11:09:56):	 DPMS mode changed: 3
[gpm_screensaver_add_throttle] gpm-screensaver.c:318 (11:09:56):	 adding throttle reason: 'Display DPMS activated': id 491953026
[mode_changed_cb] gpm-backlight.c:673 (11:09:56):	 emitting mode-changed : off
[dpms_mode_changed_cb] gpm-profile.c:654 (11:09:56):	 DPMS mode changed: 3
[dpms_mode_changed_cb] gpm-info.c:751 (11:09:56):	 DPMS mode changed: 3
[gpm_info_event_log] gpm-info.c:594 (11:09:56):	 Adding 14 to the event log

# Both monitors switched off now (internal and external). I'm hearing a "lid close" sound.

# Now I move the mouse...

[dpms_mode_changed_cb] gpm-srv-screensaver.c:196 (11:10:06):	 DPMS mode changed: 0
[gpm_screensaver_remove_throttle] gpm-screensaver.c:338 (11:10:06):	 removing throttle: id 491953026
[mode_changed_cb] gpm-backlight.c:673 (11:10:06):	 emitting mode-changed : on
[dpms_mode_changed_cb] gpm-profile.c:654 (11:10:06):	 DPMS mode changed: 0
[dpms_mode_changed_cb] gpm-info.c:751 (11:10:06):	 DPMS mode changed: 0
[gpm_info_event_log] gpm-info.c:594 (11:10:06):	 Adding 11 to the event log

# Both monitors switched on again, lid is still closed. I do not hear any sound.

# Now I'm opening the lid

[hal_device_condition_cb] gpm-button.c:393 (11:10:40):	 condition=ButtonPressed, details=switch-videomode
[emit_button_pressed] gpm-button.c:337 (11:10:40):	 emitting button-pressed : switch-videomode
[button_pressed_cb] gpm-manager.c:999 (11:10:40):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-srv-screensaver.c:167 (11:10:40):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-backlight.c:515 (11:10:40):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-info.c:698 (11:10:40):	 Button press event type=switch-videomode
[hal_device_property_modified_cb] gpm-button.c:363 (11:10:40):	 key=button.state.value, added=0, removed=0, finally=1
[hal_device_property_modified_cb] gpm-button.c:372 (11:10:40):	 state of a button has changed : /org/freedesktop/Hal/devices/computer_logicaldev_input_2, button.state.value
[emit_button_pressed] gpm-button.c:337 (11:10:41):	 emitting button-pressed : lid-up
[button_pressed_cb] gpm-manager.c:999 (11:10:41):	 Button press event type=lid-up
[gpm_control_get_lock_policy] gpm-control.c:389 (11:10:41):	 Using custom locking settings (0)
[button_pressed_cb] gpm-srv-screensaver.c:167 (11:10:41):	 Button press event type=lid-up
[gpm_screensaver_remove_throttle] gpm-screensaver.c:338 (11:10:41):	 removing throttle: id 96633217
[button_pressed_cb] gpm-backlight.c:515 (11:10:41):	 Button press event type=lid-up
[gpm_backlight_brightness_evaluate_and_set] gpm-backlight.c:376 (11:10:41):	 1. main brightness 1.000000
[gpm_backlight_brightness_evaluate_and_set] gpm-backlight.c:390 (11:10:41):	 2. battery scale 1.000000, brightness 1.000000
[gpm_backlight_brightness_evaluate_and_set] gpm-backlight.c:405 (11:10:41):	 3. idle scale 1.000000, brightness 1.000000
[gpm_backlight_brightness_evaluate_and_set] gpm-backlight.c:425 (11:10:41):	 4. ambient scale 1.000000, brightness 1.000000
[gpm_backlight_brightness_evaluate_and_set] gpm-backlight.c:433 (11:10:41):	 values are the same, no action
[gpm_backlight_sync_policy] gpm-backlight.c:159 (11:10:41):	 choosing sensible default
[gpm_backlight_sync_policy] gpm-backlight.c:161 (11:10:41):	 laptop, so use GPM_DPMS_METHOD_OFF
[gpm_backlight_sync_policy] gpm-backlight.c:193 (11:10:41):	 BACKLIGHT parameters 0 0 1800, method '4'
[x11_sync_server_dpms_settings] gpm-dpms.c:130 (11:10:41):	 Syncing DPMS settings enabled=1 timeouts=0 0 0
[button_pressed_cb] gpm-info.c:698 (11:10:41):	 Button press event type=lid-up
[gpm_info_event_log] gpm-info.c:594 (11:10:41):	 Adding 9 to the event log
[button_pressed_cb] gpm-info.c:710 (11:10:41):	 lid button OPENED
[hal_device_condition_cb] gpm-button.c:393 (11:10:41):	 condition=ButtonPressed, details=lid
[emit_button_pressed] gpm-button.c:322 (11:10:41):	 ignoring duplicate lid event
[hal_device_condition_cb] gpm-button.c:393 (11:10:41):	 condition=ButtonPressed, details=switch-videomode
[emit_button_pressed] gpm-button.c:337 (11:10:41):	 emitting button-pressed : switch-videomode
[button_pressed_cb] gpm-manager.c:999 (11:10:41):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-srv-screensaver.c:167 (11:10:41):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-backlight.c:515 (11:10:41):	 Button press event type=switch-videomode
[button_pressed_cb] gpm-info.c:698 (11:10:41):	 Button press event type=switch-videomode

# Nothing happens for the displays (they are already on). I'm hearing a "lid open" sound.

I hope I got the timing right.