Folk legend Tom Rush performed a rousing set at Symphony Hall the other night, joined by the Jim Kweskin Jug Band and a few other familiar faces from folk music's not too distant past. On stage at the end were (from far left): Bill Keith, Patty Larkin, Sarah Lee Guthrie, Maria Muldaur, Rush, Kweskin, and Geoff Muldaur. . . . A bevy of Bostonians will make their way to New York this week for Bill Bratton's swearing-in as the Big Apple's new police commissioner. (Bratton, who served as Boston's top cop from 1986-1990, held the same post in New York from 1994-96.) Publicist George Regan, a longtime Bratton buddy who hosted a going-away party at his Marina Bay abode, is attending, as are former Boston Police Commissioners Ed Davis and Kathleen O'Toole, former Boston Police superintendent Bob O'Toole, Tom Maloney of the BPD, and Northeastern's Al Sweeney.