The release date is TBA. The studio that was developing it (darkstar industries) was bought out by epic games last november which almost certainly stalled game development slightly.
This is what their website says about fat princess.
About Fat Princess
Fat Princess for the Sony PLAYSTATION®Network, developed by Titan Studios, is scheduled to be released in 2009. Sony Computer Entertainment America announced Fat Princess during its 2008 E3 Business & Media Summit keynote. Fat Princess was met with warm reception, taking home many honors including: IGN Entertainment’s Overall Best of E3 2008 Award for Best Downloadable Console Game; DailyGame’s award for Best Arcade/PSN/WiiWare Game; PlayStation Universe’s Biggest Sleeper Hit of E3 2008; runner-up, GameSpy’s Downloadable Game of Show; finalist, GameSpot’s Editors’ Choice award for Best Downloadable Game; honorable mention, GamePro’s Best of E3 2008 awards. For more information, visit http://www.us.playstation.com/PS3/Games/Fat_Princess.
