Suspend to disk works ok out of the box, if you type (as root)

  echo -n disk > /sys/power/state

I like the command line and all, but somehow this is a bit tedious. To get Fn-F12 working, one has to first load the thinkpad-acpi module

modprobe thinkpad-acpi

Next, one has to enable the hotkey subdriver

echo enable > /proc/acpi/ibm/hotkey

These two steps can be automated by creating /etc/acpi/start.d/40-thinkpad-acpi.sh Finally, workaround a problem with the default /etc/acpi/hibernatebtn.sh. For some reason, acpi_fakekey is not doing its magic thing, so I replaced it with a call to hibernate.sh. There are already some bug reports about this in debian. Now that we enabled thinkpad-acpi hotkeys, we have to the same hack to /etc/acpi/sleepbtn.sh

Be warned, this will may not play nicely with the kde/gnome gui suspend/resume tools