http://www.toonzone.net/news/articles/34425/new-series-avatar-the-legend-of-korra-premieres-in-2011 The series will focus on a new teenage girl avatar named Korra, and will take place 70 years after the events in the original series.
Her quest leads her to the epicenter of the modern “Avatar” world, Republic City - a metropolis that is fueled by steampunk technology. It is a virtual melting pot where benders and non-benders from all nations live and thrive. However, Korra discovers that Republic City is plagued by crime as well as a growing anti-bending revolution that threatens to rip it apart.
I ALWAYS WANTED TO SEE A CLASH OF BENDING AND TECHNOLOGICAL GROWTH
HOLY SHIT I AM SO JAZZED FOR THIS
ETA: New interview with Korra info:
http://blogs.wsj.com/speakeasy/2010/07/21/legend-of-korra-the-creators-of-avatar-the-last-airbender-on-the-new-spinoff/