Sure, you can do it with some digital cameras, but only one at a time. And yeah, you can fake it with Photoshop, but it's... well, faked. Also, I love that I can sell a photo and include the negative as proof that it's a one of kind work of art. The sheer providence of some of my double exposures has never ceased to amaze me. See the Mattson 2 series or the Johnny Fay roller coaster shots for example; I had no idea what was already on the roll on the second pass through the camera - let alone that the images would jive like they did. Faking it in Photoshop just isn't the same.