Choreographer and recording artist Paula Abdul is to serve as a guest judge during next week's "Dancing with the Stars: All-Stars" in Los Angeles, ABC said. Abdul previously served as judge on the singing competition shows "American Idol" and "The X Factor." She will appear on the "DWTS" judges' panel Monday, alongside ballroom expert Len Goodman and dancer/choreographers Bruno Tonioli and Carrie Ann Inaba.