There was never an official release date given for Dawnguard on either the PC or the PS3, no idea why you would think the PS3 version was meant to be out on Aug 26th. PS3 version will be out when it is ready. The only PS3 related thing they have been announcing dates for is the patches. The only DLC to get release dates is the XBox 360 versions, the other versions just seem to turn up unannounced. Bethesda officially announced the PS3 version was not yet ready, so I doubt they have any intentions of releasing it in August.