On the day he was sworn in as San Francisco's 42nd mayor 16 months ago, Gavin Newsom stood on the steps of City Hall during his inaugural address and promised: "I will tackle the smallest pothole.'' He hasn't tackled enough of them of late, as the backlog of requests now reaches into the hundreds. Faced with a mounting budget deficit, Newsom cut the number of pothole- repair crews earlier this year from three to two, and city drivers, cyclists and even pedestrians are noticing. Now, in the wake of Newsom's own bumpy ride down Seventh Avenue in the Sunset District...