All of this, disagreed. Mirror slap does indeed show an effect, in common conditions with a normal lens, even up to 1/125 and beyond. See Thornton 2000 pg65 for one published example... there are many to be found on the 'net of course. That said, proper holding or stabilization technique can mitigate though not eliminate the effect, and some bodies are more prone than others (bodies for formats larger than 35mm seem to suffer less, I'd imagine--but don't know--because of their weight).Below 1/[lens focal length] it becomes necessary to use a tripod or set the camera down on a stable surface, some for sooner than others. The duration of mirror slap is so short due to dampening that a 10 second exposure is not going to show any effect, but it may be wise to lock up a mirror on long exposures as a good practice.
Reciprocal of focal length is overly optimistic in my experience. Most folks without training can effectively handhold at one to two stops faster than that, no more. Average person seems to need 125 or 250 on a 50mm lens on 135 to get "acceptably" sharp [edit to add: at 8x10 or above, depending on the image you might not notice the effect enough to be a problem at smaller sizes]. But, that's one that people can and do argue about endlessly, so, to each their own experience.
Hey, cheers for not taking it seriously. I'm new to this forum and so far it seems much more pleasantly easygoing than most. I will say that the PhD "rocket scientists" and fluid dynamicists and whatnot that I work with have often forgotten how to tie their shoes at this point though...Since I have been an engineering professor and technically I am a rocket scientist I will ignore the comment about asking a high school physics teacher posting on line for advice.