Making suspend and hibernate working on Debian Lenny on a Thinkpad X40 with a minimal installation is pretty easy, but can become a real pain in the ass neck if you miss a step.
First of all, you must install the following packages:
haldbusconsolekitacpiduswsuspgnome-power-manager
Then, add youself to the powerdev group:
adduser <login> powerdev
Make sure thinkpad_acpi kernel module is loaded.
If you want to be able tu use the Thinkpad (or Access IBM) blue button, you must edit /etc/acpi/thinkpad-thinkpad.sh and replace acpi_fakekey $KEY_PROG1 by acpi_fakekey $KEY_MACRO (for an unknown reason, it seems that Xorg is not able to retrieve $KEY_PROG1 (#148) keycode from /dev/input/eventx). The keycode associated is now 239, you can bind it using xmodmap or xbindkeys.
Don't forget to put gnome-power-daemon on your session startup script (~/.config/openbox/autorun.sh in Openbox).
You should now be able to use either special shortcuts such as Fn-F4/Fn-F12 and gnome-power-manager buttons in the tray icon.