I have a clean install of Debian Unstable on my Thinkpad X41. Everywhere I look it says that acpi should work out of the box. I can tell by the log file that my lid.sh script is getting executed but it is not putting my laptop to sleep. After experimenting a bit I noticed that typing (as root) echo mem > /sys/power/state does nothing!
I've had other distro's on the laptop (Arch, Suse, Ubunut) and that command never fails to put the laptop to sleep. (Waking is a different story.) What could I be missing since that command is not functioning? I did do an apt-get install of acpid and acpi.