Here’s an even more compelling video by a guy who looked a HEX Editor of the Obama image file, where it’s clearly got “Photoshop” mod traces!!!
http://www.youtube.com/watch?v=SIsQJNTvlUE
I believe one can use photoshop to acquire an image (as from a scanner). That could be the source of the "Photoshop" (on a Mac no less) information inside the metadata of the image. Or maybe not. It wouldn't be my first choice, and you can scan in images with cheaper or free programs, including ones likely to come with a Mac or PC (such as "paint" on the PC). Still someone who deals with images a lot, like my wife, and had Photoshop, might choose to use it instead, based on familiarity and perceived ease of use.