Get the "Obama effect" in Photo Booth with the Obamafy plugin
Once you've downloaded the .qtz file, move it to Compositions in your Library folder. Once you've done that, open up Photo Booth and click effects. You might have to cycle through to the last page of your effects to find Obamafy, but it should be there. It took a little bit of experimenting for me to find the right lighting to get a result that looks like the posters, so don't give up without playing around a little bit.