OK, this is geeky and stupid.
When starting up Mac OS X 10.4 (Tiger), a window displays with a blue progress bar:
It turns out that that window is simply a place-holder until the LoginWindow process can launch. The progress bar? It does nothing, it measures nothing beyond guessing how long it will take before the LoginWindow process will come up, which it then uses to move the progress bar this time.
More details can be found here. The WaitingForLoginWindow process even logs how long it took to run, and has a freakin’ man page!
That’s stupid! I can’t believe that such a thing actually exists. I and other techs have joked about such a thing for years, but for someone to actually build an example and include it in a major release as some kind of tech placebo is beyond me.