Somewhere in the bluegrass beyond, Bill Monroe is wondering just what the hell happened to Ricky Skaggs, the blue-eyed Kentucky boy he once lifted on stage to play the mandolin for the faithful, thereby baptizing a great country career. If traditionalists can forgive (and even secretly savor) his mainstream hits in the '80s, Skaggs will have to forgive them for considering a cover of Rick James' "Super Freak" with piano popster Bruce Hornsby as flat-out bonkers. And it is bonkers, but also disarmingly fleet, as is much of the duo's self-titled 2007 album, a collaboration that does less to retool Hornsby's AOR style for NPR affiliate stations, and more to see what strangely familiar sparks fly when two masters of American music toss tradition out a wide open window.