Software to find desktop power usage?

Since I have moved from Windows XP to Ubuntu 12.10, I have been constantly blamed for increased electricity bills.(That may be true, but I think the reason is increase in the time I use my computer, because it is more productive now).

Is there any software that would calculate how much power my computer actually uses?

Note that I use a Desktop and the Powertop, Powerstat, and Power Statistics programs referenceed here only work for laptops. The answer suggests that for desktop the only solution "then" is to use a electronic watt-meter. Has the situation changed in last 2 years?

Solution 1:

We have created a terminal tool to monitor CPU frequency/utilization/Temperature. It now also supports monitoring power on Intel CPUs newer than Sandy-Bridge.
You can see the power graph in watts on the bottom as well as on the side bar.
This only reads total CPU power, not per process and not including other components.

Solution 2:

The simple answer is: You can't by software

powertop seems to be fair in this situation

Use an electronic watt-meter

In instance check this link from intel