Former Cox exec William Stemper was appointed pres, Comcast Business Services, and svp, Comcast Cable. — Charles Hirschhorn was elected a board member of Playboy. — Nielsen Media Research named Catherine Herkovic GM, local business unit. — Food Net promoted Bruce Seidel to svp, program planning and special productions. — Showtime Nets elevated Tracey Wolfson to vp, ops and distribution.