The latest issue of Wired magazine(5/17/09 - not yet posted to the website) analyzes a can of WD-40. Ingredients include chemicals called alkanes, which lower the freezing temperature and repel water, and dimethyl naphthalene, which helps dissolve adhesives and grease. The liquid base is mineral oil and the propellant is carbon dioxide.
On Friday the Environmental Protection Agency declared carbon dioxide to be a greenhouse gas that "contribute[s] to air pollution that may endanger public health or welfare".
Engineers, mechanics, gardeners, and metal workers of the world unite! They will pry our WD-40 from our cold, dead hands.