From ‘Cabaret’ to Kanye, Songs of ‘Glee’ Are a Hit; New York Times, 10/12/09

Edward Wyatt, New York Times; From ‘Cabaret’ to Kanye, Songs of ‘Glee’ Are a Hit:

"Ryan Murphy, the creator of the series, said in an interview in May that the search for music has been an integral part of the script development. “Each episode has a theme at its core,” he said. “After I write the script, I will choose songs that help to move the story along.”

Clearing the rights to the music for the series has not been a problem, he added. “I can’t think of one artist we’ve gone after or a song I wanted that has been denied.”"

http://www.nytimes.com/2009/10/12/business/media/12glee.html?_r=1&scp=1&sq=glee&st=cse