Bethesda has "tried a number of things, but none of them solve the issue enough to make Dawnguard good for everyone." The post notes further that Bethesda is also working on more content for Skyrim – the "Hearthfire" expansion was revealed earlier this week – which makes the situation "even more complicated," presumably referring to the resources needed to continue working on Dawnguard.
The company continues, offering perhaps the most troubling statement for PS3 owners, "This is not a problem we're positive we can solve, but we are working together with Sony to try to bring you this content." Bethesda notes the "frustration" PS3 users must be facing, and promises an update as soon as possible.
We've contacted Bethesda to see if we can learn any further details on the issues facing the PS3 version.