Comment 26 for bug 365798

The modules mentioned in the PDF guide you posted are not available in Jaunty:

 sudo modprobe speedstep-centrino
FATAL: Module speedstep-centrino not found.

 sudo modprobe acpi-cpufreq
FATAL: Module acpi-cpufreq not found.

since they are built into the kernel.

I've tested a fourth machine, this time a Core 2 Quad desktop computer:

 find /sys/devices/system/cpu/cpu*/cpufreq
find: `/sys/devices/system/cpu/cpu*/cpufreq': No such file or directory

3 out of 4 Intel machines I've tested do not support cpufreq with kernel 2.6.28-11-generic. This has been working for ages on other kernels.