Hi Rafael, Matthew,
my laptop changed behavior during poweroff recently (after upgrading
from .33 to .34-rc1). The system seems to be powered off (status display
is off) at first glance but when I close the lid then I can hear a noise
which sounds like HDD parking and when I open lid again it starts
booting without poweroff button (same like when I suspend to RAM).

I have bisected that down to the following commit:

commit 9630bdd9b15d2f489c646d8bc04b60e53eb5ec78
Author: Rafael J. Wysocki <rjw@sisk.pl>
Date:   Wed Feb 17 23:41:07 2010 +0100

    ACPI: Use GPE reference counting to support shared GPEs

    ACPI GPEs may map to multiple devices.  The current GPE interface
    only provides a mechanism for enabling and disabling GPEs, making
    it difficult to change the state of GPEs at runtime without extensive
    cooperation between devices.

    Add an API to allow devices to indicate whether or not they want
    their device's GPE to be enabled for both runtime and wakeup events.

    Remove the old GPE type handling entirely, which gets rid of various
    quirks, like the implicit disabling with GPE type setting. This
    requires a small amount of rework in order to ensure that non-wake
    GPEs are enabled by default to preserve existing behaviour.

    Based on patches from Matthew Garrett <mjg@redhat.com>.

    Signed-off-by: Matthew Garrett <mjg@redhat.com>
    Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
    Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

When I revert this commit, the system behaves like before. I am not sure
which kind of information might be useful so I have attached only config
file for now. The laptop is Futjitsu Siemens Lifebook S Series.

Let me know what else might help for further investigation.

Thanks
and
best regards
-- 
Michal Hocko
L3 team 
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic