Yeasayer at Virgin Free Fest (09/25/10) Photo: Jon Klemm (more) The Prom You Were Promised: A Benefit for 826NYC (09/13/11) Hosted By Jason Sudeikis (Saturday Night Live, Horrible Bosses) and Featuring DJ Sets By Yeasayer, BAIO (Vampire Weekend), Neon Indian and CANT 18 AND OVER WITH ID Sep 13 The Prom You Were Promised:…