The new model from Audi, expected to be the successor of the A2, will be likely called A1, with a similar design as the 2005 Audi Shooting Brake concept. Based on the Golf IV PQ34 platform, the A1 should be launched in 2009 at the Frankfurt Motor Show (sedan) and in 2010 (convertible).
Here is a review on this new model, with info and impressions on its features, design and cost, as well as a bit of history regarding mostly the Audi Shooting Brake concept, and the competition the Audi A1 will like face: the C30 model from Volvo.
"There were many rumors about the Audi Shooting Brake concept going into production. Early information showed that it was supposed to be placed above the TT as a sportier model. Updated sources, though point that the new car will be a sub-compact, positioned under the A3..."
The whole article is here: http://www.topspeed.com/cars/audi/audi-a1-ar13219.html