Over the past six months, Hockney has fashioned literally hundreds, probably over a thousand, such images, often sending out four or five a day to a group of about a dozen friends, and not really caring what happens to them after that. (He assumes the friends pass them along through the digital ether.) These are, mind you, not second-generation digital copies of images that exist in some other medium: their digital expression constitutes the sole (albeit multiple) original of the image.
That's Lawrence Weschler writing in the New York Review of Books about David Hockney's iPhone drawings. Read the whole thing, of course. Hockney also shares this interesting observation with Weschler:
I asked Hockney whether he'd mind my sharing some of these images with a wider audience across a printed medium, and he said, not really, he more or less assumed that the pictures would one by one find their way into the world. "Though it is worth noting," he adds, lighting one of his perennial cigarettes, "that the images always look better on the screen than on the page. After all, this is a medium of pure light, not ink or pigment, if anything more akin to a stained glass window than an illustration on paper."