Does anyone know when the new season of Entourage starts?

Answer 1

Wikipedia said: The 12th episode of the third season, "Sorry, Ari", aired on August 27, 2006. The remaining eight episodes of season 3 will be aired early next year.
IMDB says:
Season 3, Episode 13: Vince's Birthday
Original Air Date: 2006

Season 3, Episode 14: Dog Day Afternoon
Original Air Date: March 2007

Season 3, Episode 17: The Return of the King
Original Air Date: 2006

Season 3, Episode 18: The Resurrection
Original Air Date: March 2007

TV.com says :
Next episode: Dog Day Afternoon

Airs: Sunday March 18, 2007

Hope this helps=)