The program Hardware Monitor, it is possible to read all sensors in your Mac. This little program Hardware Monitor reads all sensors in your Mac computer, such as temperature.
For the most part it's just fun to read the many sensors, but they can obviously also be used for something more serious, if you must troubleshoot a computer. Hardware Monitor 4.95 has just been released and adds support for iMac (Mid 2011), MacBook Air (Mid 2011), Mac mini (Mid 2011) and Mac Mini Server (Mid 2011).
Hardware Monitor is on sale for 7 Euro.