Guardian: The Obama administration unveiled a $4bn (£2.5bn) plan to upgrade public housing for low-income Americans today, as part of an ambitious green job-creation project. Obama sent the vice-president, Joe Biden, and other senior officials to Denver for a formal announcement of the renovation scheme, which will replace windows, insulation and even light bulbs in ageing and neglected housing stock. The labour secretary, Hilda Solis, was also expected to announce $500m to train up …