on the february 25th episode of jimmy fallon, itzhak perlman sat in with the roots, playing during the opening theme, accompanying the keyboardist during the regular 'thank-you notes' sketch, as well as playing for the other musical segues, including stormy weather.
as best i can tell it's his first appearance on a late-night show since 1994, and i assume his only ever sitting in with the house band. his appearance was intended to promote the ongoing efforts to end the spread of polio, which is still extant in some countries.