Penn indicates that Nicholson Baker is the greatest writer today, and I certainly agree that Baker is just terrific. Penn turned me onto him in an article for Reason magazine many years ago, praising The Mezzanine. He repeats that praise in his blog on "House of Holes."
Given Penn's intellect, I'd be surprised if he hadn't read Richard Powers. In my estimation, Powers is miles ahead of anyone else writing today, and he's right up the alley of anyone who enjoys the same level of thinking about things as Penn and his fans.
I was introduced to Powers through his novel, The Gold Bug Variations, having to do with Bach, information theory, and love. From there, i picked up Three Farmers on the Way to a Dance, a detailed examination of a pre-WWI photo a la The Mezzanine, which Baker evolves into three biographies of the photo's subject.
My favorite might be The Time of our Singing, and examination of civil rights through the eyes of two mixed marriage music prodigies, who parents were a German Jewish physicist and a Philadelphia singer who meet by chance at the Marian Anderson Washington Mall concert. This was the concert moved to the Mall because the Daughters of the American Revolution would not permit a performance by a black woman in their hall.
Like Baker, Powers' prose is witty and profound, but Powers dazzles with his poetic language.
Baker and Powers both come from a music background, both having pro level chops, so maybe there's something in that.