Three years ago, Arlington, Virginia, was pitching itself as the next Silicon Valley. Victor Hoskins, the county’s director of economic development, tried to lure entrepreneurs with cash prizes, free housing, office space and other incentives. Few showed up. Then, after a courtship lasting more than a year, Arlington landed the opposite of a startup: Half of a second headquarters for Amazon.com Inc. Amazon’s arrival looks like a panacea for Arlington’s economy, which has been hurt by the flight of defense industry jobs. Amazon says it will hire more than 25,000 people and spend about $2.5 billion in the area. Click here for more information.