The Official Website and Trailer has been released
The original release date for the movie was supposed to be in winter 2006, but they moved it for reasons still unkown. Here's a short description of the movie.
When King Harold falls ill, it is up to Shrek to find a suitable heir or he will be forced to give up his beloved swamp for the throne. Recruiting Donkey and Puss in Boots, Shrek sets out to bring back the rightful heir to the throne, Fiona's rebellious cousin Artie (Timberlake). Meanwhile, in Far, Far Away, Fiona's jilted ex-fiance Prince Charming storms the city with an army of fairy tale villains to seize the throne, not knowing that Fiona, together with her mother, Queen Lillian, has drafted her fellow fairy tale heroines to defend themselves. As Shrek, Donkey and Puss work on changing Artie from a royal pain into a future king, Fiona and her band of princesses must stop Prince Charming to ensure that there will be a kingdom left for Artie to rule.
