Cover art by Anthony Ausgang
And here's a little info courtesy of Boing Boing's interview with the artist:
How did you get hooked up with MGMT?
I met Andrew and Ben from MGMT through the experimental musician Sonic Boom of Spacemen 3 and Spectrum, for whom I had done album cover art in the past. MGMT was recording "Congratulations" at a mansion in Malibu so I went there a couple of times to hang out and watch the process unfold. Not being a musician I was occasionally left to my own devices so I would sit around and draw on pieces of paper then leave them there when I went home. I got along well with the band and gave them copies of my book, Vacation From Reality. Later, Josh Cheuse, the art director from Sony, contacted me once the recording was finished. The most important thing was that MGMT wanted the "look" of my style of painting and gave me only a few points that I had to hit. Naturally the process took some time but they were always cool with the criticisms. A lot of people who commission a painting only know what they don't want; fortunately MGMT knew what they wanted and let me do it my way.