You can add God of War: Chains of Olympus to the list of games you'll be playing... next year. Originally scheduled for a holiday release, the game's release window has now been shifted to Q1 2008.
A reason for the delay was not given. Although, despite the delay, it's a good thing we still have the UMD demo to look forward to in September. That, along with other PSP games coming out during next couple months, such as Castlevania: Dracula X Chronicles and Syphon Filter: Logan's Shadow, should be enough to tide us over.
Confirmed: God of War PSP delayed until 2008 [Pocket Gamer]