Got the solution - originally, I've installed the system with
                --noapic \
                --noacpi \
Omitting those options, I get this into the xml used during installation:
  <features>
    <acpi/><apic/><pae/>
  </features>
and then after installing and starting acpid, shutting down works like a charm.

What was hard though, was to add those features later in the xml, even installing acpid wasn't any use, had to reinstall with the above procedure. But now I know how to proceed.
Thanks,
Regards
Michael

Am 03.06.2012 01:35, schrieb Trey Dockendorf:
What /etc/init.d/acpid restart return or show in /var/log/messages?  Minimal should work fine as that's what I've always used to provision KVM guests.

On Sat, Jun 2, 2012 at 6:14 PM, Michael Kress <kress@hal.saar.de> wrote:
Am 02.06.2012 18:02, schrieb Trey Dockendorf:

On Jun 2, 2012 10:43 AM, "Michael Kress" <kress@hal.saar.de> wrote:
>
> Hi, shutting down a Centos6 kvm guest does not work from outside doing a
> 'virsh shutdown vmguest', I've installed the
> CentOS-6.2-x86_64-minimal.iso
> inside the kvm guest
>

If acpid is installed try rebooting.  Ive had issues with acpid starting on first install as its blocked by another daemon.  Rebooting or installing during kickstart has solved it for me.

- Trey



I've done that numerous times, no success.
Will try with the regular version of Centos 6 and report again.
Regards
Michael