RTC device behavior in Linux

Linux features a command called rtcwake which can - turn the computer off - suspend to memory - suspend to the hard drive - .. some other power saving mode and then turn it back on using the computers motherboards rtc device. Using Ubuntu Server 11.X and rtcwake with the "off" option was working as expected. On the very same machine with Ubuntu Desktop 10.10 after executing rtcwake the computer stays on with the rtcwake programm giving back control to the command line without giving any feedback (no error, no success message). How to "install" the "off" option (and other options) to work with rtcwake.