I'm not sure whether that will be the case for the next update already. The difficult thing for OG to actually use WebKit is to still offer the advanced functionality, which they used to program into their own version of WebCore.
According to my sources, they're working on it. But they're probably going to face the question: "Should we sacrifice some features and stay up-to-date with current WebKit (using the one installed by Safari) or should we stay focused on the advanced functionality?" - And for most users who're paying licensees of OW, the latter is probably more important.
But if they can cut their changes to WebCore down, they can probably more quickly adopt new versions of WebCore, which would make things quicker, too.