Rihanna's new song features Kanye West ... and Paul McCartney

In news regarding people-we-don't-usually-include-in-the-same-sentence, Rihanna and Kanye West have teamed up with Paul McCartney to create an acoustic song.It's called "FourFiveSeconds." The track isn't on YouTube yet, but you can it download it for $1.29 here. It debuted Saturday accompanied by a black and white photo of the trio dressed in matching denim.