MORE SIMPSONS GUEST STARS: Other confirmed guest stars for the new season include several Glee cast members and Flight of the Conchords for the season premiere; Mad Men’s Jon Hamm, who’ll play an FBI agent; Daniel Radcliffe and Alyson Hannigan in this year’s “Treehouse of Horror” Halloween episode; and Martha Stewart. And Russell Brand says he's been asked to lend his voice to an episode as well. (7/29a)