There are some «good news» from the Linux world: currently, their CPU frequency scaling works effectively just as good as ours.
Actually, Linux has some advantages. They have ACPI CPU controllers, they read the CPU frequency data from ACPI and use ACPI to set the frequencies. This means that they can indeed set more frequencies.
However, they are not capable for some reason to set the CPU frequency to a value below 1GHz. Some FAQ declares that this is a limitation of the Intel Core 2 series, but this is indeed not the case. FreeBSD can set the frequency to 1997MHz, 1747MHz, 1497MHz, 1248MHz, 998MHz, 748MHz, 449MHz and 249MHz. This is well below 1GHz.
So I guess the correct solution is really to port FreeBSD's acpi_throttle driver.