When does Flight of the Conchords return?

Flight of the Conchords is an American sitcom that was first shown on HBO on June 17, 2007. The show follows the adventures of a struggling two-man band from New Zealand, as its members seek fame and success in New York City. Jemaine Clement and Bret McKenzie play fictionalised versions of themselves and their band. The series received 10 Emmy Award nominations, including "Outstanding Comedy Series"