Time to barricade Fort Adams State Park, because the hip, the cool, and the disaffected will be descending on the annual NEWPORT FOLK FEST this summer. In what's a pretty impressive overall lineup, the two-day July 30 and 31 folk fest under the Rhode Island sun will this year feature the Decemberists (those bastards that ruined indie rock, remember), Tegan & Sara (two ladies often saddled with saving it), Elvis Costello, Emmylou Harris, and a host of other notable acts, revealed last night at the Middlesex Lounge in Cambridge, including Gogol Bordello, Carolina Chocolate Drops, Gillian Welch, Mavis Staples, Freelance Whales, Delta Spirit, Pokey LaFarge and the South City Three, What Cheer? Brigade, Felice Brothers, and our very own David Wax Museum, which got NPR all flustered after last year's performance.