Theres an ongoing development around netkas's fakesmc source. The new features are super-IO chip readings (temp, fan speed, voltages), GPU temp/fan readings for Nvidia cards and GMAx3100, ACPI register readings and CPU temps. The screenshot is from my P5K-VM board using iStat. The kexts are still being actively developed at the moment.
For more details you can check out the original thread
For more details you can check out the original thread