A massive network of employment Web sites - where any company can list job openings for free - launched this week over the protests of newspapers and online recruitment companies, who fear billions of dollars in lost revenue. The 40,000 sites, with Web addresses that all end in ".jobs," have the potential to upend companies such as Monster.com and CareerBuilder.com, which just a decade ago set up for-profit jobs classifieds online that roiled the media companies that printed the listings on paper. The initiative is being backed by nearly 600 hundred industry titans such as Google, American Express, IBM, Northrop...