Joss Whedon’s “Dollhouse” and “Dr. Horrible’s Sing-Along Blog” are the latest additions to the Paley Center for Media’s upcoming Paleyfest ’09.The full fest schedule will be disclosed Feb. 18. Several weeks ago, HBO’s vampire drama “True Blood” and Fox’s sci-fi drama “Fringe” were announced. “Dollhouse,” about a woman who can have her brain downloaded to fit a specific mission, begins airing on Fox this Friday. “Dr. Horrible,” starring Neil Patrick Harris, was a 43-minute Internet sensation that launched in the summer. The Paleyfest will take place April 10-23 at the Cinerama Dome in Hollywood.