Here's what's happening on the Nov. 9 episode of NYPD Blue: Two people are stabbed, two businesses are robbed, and Medavoy (Gordon Clapp) moonlights as a security guard. Oh, and Bobby Simone comes back from the grave. ABC is being understandably tight-lipped about the reappearance of the character, a November sweeps month stunt to goose the ratings of the show's 12th and final season, except to acknowledge that Jimmy Smits is returning, for one night at least, to reprise the detective role he played for five years, until the ailing Simone died in Season 6 in one of the weepiest hours in TV history. No word on how the show will explain his reappearance, but the episode is titled ''The Vision Thing.'' So maybe Simone's former partner Sipowicz (Dennis Franz) sees him in a ghostly vision. Or maybe we'll find out, à la Dallas or St. Elsewhere, that the last several seasons have all been somebody's dream.