Just noticed that in openSUSE 12.x, A plain halt will not shutdown the system properly.
On my system, it would leave the screen as shown on the right:

Only halt -p works, none of the other hints in the shutdown does not power off thread work, nor the acpi=off or acpi=oldboot settings.

The odd thing: a plain reboot still works properly.

If someone knows a better workaround: please let me know in the comments.

I hope they will fix this in a future openSUSE version; at least for 12.1 they have a “CHECKIT” marker in the documentation, but it has disappeared as of the 2.3 docs, but still fails:

CHECKIT for 12.3. Is this entry still required?

To halt and poweroff the system when using systemd, issue halt -p or shutdown -h now on the command-line or use the shutdown button provided by your desktop environment.

Note: A plain halt will not shutdown the system properly.

Luckily, my openSUSE is a VM, which I can reboot from the ESXi host.
On a physical system, you will end up without any option to resurrect the system.

Later

After installing antivir, a plain halt works sort of: it says it is halted, but ESXi still thinks it is not:

After installing antivir, a plain halt appears to work, but it doesn’t.

ESXi is sure the system didn’t actually power down.

–jeroen