This New York Times feature has a representative slide-show:
Vivian Maier, evidently one of Americaâ€™s more insightful street photographers, has at last been discovered. The release of every fresh image on the Web causes a sensation among the growing legion of her admirers. … Ms. Maierâ€™s streetscapes manage simultaneously to capture a redolent sense of place and the paradoxical moments that give the city its jazz, while elevating and dignifying the people in her frames â€” vulnerable, noble, defeated, proud, fragile, tender and often quite funny. …
What is known about Ms. Maier is that she was born in New York in 1926, lived in France (her mother was French) and returned to New York in 1951. Five years later, she moved to Chicago, where she worked for about 40 years as a nanny, principally for families in the North Shore suburbs. On her days off, she wandered the streets of New York and Chicago, most often with a Rolleiflex twin-lens reflex camera. Apparently, she did not share her pictures with others. Many of them, she never saw herself. She left behind hundreds of undeveloped rolls.
Vivian Maier blog
Russell Bowman Art Advisory Exhibition, Chicago, April 15, 2011 – June 18, 2011
Finding Vivian Maier: Chicago Street Photographer exhibition, January 8, 2011 – April 3, 2011
Vivian Maier, 1926-2009
Hat tip to Xavier.