Who’s the hopemonger (to borrow John Heilemann’s term for President-elect Barack Obama) of high-density construction in Manhattan? Extell Development chief Gary Barnett. We recently caught up with Barnett, who stands apart from his peers as he continues to push projects through construction: The ecoefficient Lucida condo on the Upper East Side will open next year and a 600-room hotel just east of Times Square just came out of the ground last month. While Barnett got shut out of the Hudson Yards deal and has relatively few friends in the city’s real-estate elite, he also has enough land (including the onetime Trump portfolio at Riverside South) to look past the current economic crisis. “It’s no fun to go through, but when you look at it from 30,000 feet, it’s not a bad thing for the market,” said Barnett, who admits to letting go of 10 to 15 percent of his staff in this bear market — but sees brighter days ahead. “This is not like the early nineties, where there was a huge overhang of inventory. On the residential side there’s almost no vacancy.” While megaprojects like Hudson Yards founder, Barnett says Extell will draw on its land bank to deliver new residential projects in as soon as nine months.