Gametrailers was fortunate enough to interview Jesse Abney, the producer for upcoming game Need For Speed: Shift.
In the interview, Jesse reveals how Shift allows players to experience an even more realistic simulation of street racing, and that Shift will not be an open-world title. Another point Jesse made was a demo will be released on PSN in the Summer, and that the release date for the full game is set for September 2009.
[Source]