I'm bringing up SL4.4 on my Thinkpad T30.  After messing around with acpi
scripts, the ibm_acpi driver, and all sorts of other frobbing, I was 
never able to get the backlight and display to go out when I suspend. 
Apparently, this requires a later kernel than 2.6.9, or patching the 
kernel I have - which I can do, but often breaks dependencies for
updates and upgrades.

The Thinkpad ran just fine for years with 2.4.22, which came up with
apm instead of acpi by default.  So I gave up on acpi, and changed
the kernel line in /boot/grub/grub.conf to turn off acpi:

   kernel /vmlinuz-2.6.9-42.0.3.EL ro root=LABEL=/ acpi=off

With acpi off, apm is enabled automagically in its place, and the
apmd service starts also.   apm suspends the display just fine,
just like it did with the old kernel.

I look forward to SL5, where I imagine that acpi and the radeon driver
are patched up to the point that suspend works properly (among other
things, the ibm_acpi module is part of the kernel tree).  All sorts
of wonderful things will be possible with 2.6.18 and acpi, like 
ultrabay hotswap and software control of many BIOS parameters.

Unfortunately, my attempt to upgrade SL4.4 to SL5alpha with the
rsynced rpms failed in a morass of dependencies, so I will wait for
the betas to appear before I dive in.  

Keith

-- 
Keith Lofstrom          [log in to unmask]         Voice (503)-520-1993
KLIC --- Keith Lofstrom Integrated Circuits --- "Your Ideas in Silicon"
Design Contracting in Bipolar and CMOS - Analog, Digital, and Scan ICs