Anyone tried the ACPI alarm rtcwake function in openSUSE 11.0.
Is it working?

It was broken in openSUSE 10.3 - it hope it is fixed in openSUSE 11.0 - but my first tests failed.

When I echo a date into /sys/class/rtc/rtc0/wakealarm the file stays empty for some reason.

This command should set your machine to wake in 5 minutes:
echo "+00-00-00 00:05:00" > /sys/class/rtc/rtc0/wakealarm

Put SYSTOHC="no" in /etc/sysconfig/clock so that the bios clock is not touched when you shutdown.