David Cox, producer on Castlevania: Lords of Shadow, has been all over Twitter recently, responding to complaints about the DLC delay. When he was asked by one disgruntled European gamer wondering why the Xbox 360 delay was holding up the Reverie DLC on PS3 in his region, Cox revealed that the initial DLC launch on PSN was "put up there in error." In other words, Reverie wasn't meant to be released on PS3 in North America (whoops!).
Cox also said that it's "too late to take it down" meaning that presumably whatever bug is keeping it from a larger release isn't catastrophic enough to require it be pulled from Sony's service. Currently the DLC is still available on the US PlayStation Store for $9.99.