He sounds every bit as good as Steve Perry did on that; I have to say, it shocked the hell out of me, but then again, tons of musicians are great singers and they go unknown as singers.
Remember the Coors Light commercials with the guy with the raspy voice singing "Coors Light, It's the right beer now!"
That is Will Lee singing that - he's the bass player on David Letterman's show.
Another great singer is Pat Torpey - drummer from Mr. Big; he sang vocals as a background vocalist for YEARS. One of his credits is he sang background vocals on Motley Crue's "Girls Girls Girls" release.