Latest rawhide Aug 23 echo 1 > /proc/acpi/sleep says something like "stopping tasks" (flashes very quickly) and then the laptop returns to its normal state instead of suspending. This is with acpi enabled. In FC2 acpi was broken, but it sort of thought about working (it worked sometimes, and sometimes locked up), IIRC. APM worked OK in FC2 and I haven't yet tried in rawhide.
Current rawhide (and FC4 was fine too) suspends fine on my x31. Havoc -- come talk to me if yours still doesn't work :-)
Will have to test again, I haven't tried ACPI in a while.