Wow, that's really a ncie looking article! I skimmed through it and it looks well-written too - and I love the cracked LCD cover in the illustrations :-)
A coupe of minor observations:
"A series K mount lenses (like the 50mm f/1.7 shown above) can be thought of as essentially manual focus lenses on a Pentax DSLR."
Took me quite a whiel to parse this. At first, I thought the subject was "series K mount lenses", and I wonder why you would use the indefinite article "A" since the subejct was plural. Then I realize you must have meant "A series" lenses. I'd suggest either putting the "A" in quotes, or eliminating the phrase "K mount", or putting the word "The" in front of the whole shebang. Actually, though, I'm not sure the sentence really says much - *of course* they are manual focus lenses. So are the M's, and also the M42's. Maybe you meant to emphasize that focus is the *only* thing manual about them?
Overall, I'd consider putting the M stuff before the A stuff, because way more people have M than A, and it might take them a while to wade through to find the stuff about the aperture ring. Or maybe put a link toward the top to let them jump right to where they need to be.
You should mention difference in models as far as what have what type of button to press to set the exposure (*ist D, K10D, K20D, K200D = green; *ist DS, *ist DL, K100D, K110D = AE-L, K-m/K2000 = "+/-", I believe). Also, be aware that the meter display you get via DOF Preview is only a bar graph on the K10 & K20D - it's numeric only on all other models as far as I know. And the K-m/K2000 lacks the DOF Preview entirely.
Sean Nelson, as you may know, wrote what has been the definitive guide thus far, in a thread on dpreview:
K100D (Super) Pictorial guide to using manual lenses [imgs]: Pentax SLR Talk Forum: Digital Photography Review
His has a certain step-by-step simplicity worth looking at, and if nothing else, providing a link to.