At 4:00am most of the Linux (and UNIX for that matter) machines start executing a bunch of scripts that clean up temporary files, update file databases, and all sorts of other maintainence work. For those, who know, I am talking about cron daemon. Obviously, such a heap of activity increases the power consumption of each individual computer and thus can be monitored by the electricity authority. And probably it is. The useful thing here is that this monitoring can be used for estimating the number of Linux/UNIX machines in the geographical area, such as a region, city, or, even, a country.