While a release date delay for a horror movie typically indicates a studio has a lemon on their hands, that might not be the case with the latest from Paul W.S. Anderson. Jovovich's tweet on the matter said that, were it to occur, the delay would be because post-production on the 3D rendering could not be completed by the required July deadline. So now that the delay has been confirmed, it is a safe assumption that dealing with the added dimension for the first time is what caused the slip.
Coincidentally enough, this new release plan puts RE:A up against The Cabin in the Woods, the horror movie co-written by Joss Whedon and directed by Cloverfield's Drew Goddard that also settled on the 01/14/11 date after its own delay in converting the film to 3D. By that time the number of screens in the US capable of displaying 3D movies will have drastically increased, but even still, don't be surprised if either film shifts forward or backward for some box office breathing room as the date gets closer.
In the mean time, Screen Gems has given the original August date to the Paul Bettany starring Priest, an adaptation of the holy-man-kills-vampires comic of the same name.