What's true to life? The usenet posting rule that says if people resort to calling each other Nazis after a long flame war, the discussion has outlived its usefulness? Or the idea that the Third Reich is off-limits in any and all discussion of politics and history?
As a rule of thumb in the world of internet flame wars, I suppose Godwin's observation (sorry, "Laws" do require authority if I'm going to abide by them) was accurate, if not redundant. As a mechanism to erase the lessons of the Third Reich from political discourse altogether, it's absurd and dangerous. I don't know if the latter was Mike Godwin's intent (knowing something about him might help in understanding that), but I know that's what it's become. In its present form, it's a specious trump card for terminally lazy cyberpundits.
Tell me, should "Godwin's Law" be invoked if someone makes the obvious analogy in a discussion about the Islamic Republic?