I saw that before.. but what really threw me today is the one guy claiming that focal length doesn't affect dof... maybe I read it wrong.. but ugh.
Focal length can affect DoF - it just depends on what else you do or do not hold constant. If you change focal length without changing subject distance, you're changing DoF. If you change subject distance without changing focal length, you're changing DoF. In each case, you're changing the magnification - the size of the subject. But if you keep the size of the subject constant (e.g., move closer as the focal length gets shorter), then DoF remains constant for a given aperture - that's why the statement that DoF depends on magnification and aperture is a better way to phrase it.
Put another way, DoF is determined by magnification and aperture, and magnification is determined by focal length and subjet distance.
I'm at work so I skimmed it... but I'll give it a real look when I'm free from my shackles.