It shouldn't be too hard for someone to write a widget for the dashboard to handle the ACPI thermal stuff if it's supported on their hardware. I have had it on my to-do list for probably two years now but haven't found the time and inclination to make it. :-)
Oops I was not trying to be offensive, by indicating "…not too hard for someone"...!
Nothing offensive anywhere there, just saying that if someone had hardware that was supported by that method and knew some PHP coding it might be easy to write for someone who was interested in taking that on. It would certainly be more lightweight than a full-blown phpsysinfo package, and wouldn't require any extra software. Just a sysctl command and parsing the output.