The online version (photo is hyperlink) is an excerpt; it doesn't have the print edition's appropriately/trippily stylized graphic design, with long one-line quotations scrolling, in varying font size, across photographs on multiple pages (Since when was Nat'l Geo so design-y?), but you can get a taste, and there are some good links. This morning I got as far as the reference to the famous quotation of Paul Erdős, "a mathematician is a machine for turning coffee into theorems" (it didn't mention his purported affinity for amphetamines), and I did read of caffeinated gum, but I don't yet know whether the piece references the caffeinated soap somebody was asking about in ann_arbor_ypsi a while ago.
One cool thing not online is a series of images of brain activity of heavy users when not on caffeine (only a little), of heavy users when on caffeine (quite a lot), and of light users when not on caffeine (much more than the first category). Hope to get another look at the article in hard copy some time---it also has more of the cross-/multiple-cultural examination of the subject you'd expect from the magazine, and more on psychoactivity associated with the stuff.