The xx's (iTunes) new album Coexist comes out September 11th, 2012. I love their music. They are classified as alternative, but I think it's a little more like ambient alternative with their very chill, soothing melodies.
Definitely check out their eponymous debut album, The xx, as well if you like what you hear.
If you have a chance take a listen and take a look at their data visualization that tracks how their music is shared. The visualization is pretty cool at seeing how the hmm... not the social network, but rather the human network of people sharing between distant places.