Mansurov recently published an article that aligns with what I thought happened. Net: the tsunami in Japan and the Thailand floods caused a delay. The delay got bigger when Nikon realized they'd wind up with a camera too far behind the D7100 so they delayed again and stepped up the design.
Whether it is true or not should be known by January (CES), or possibly sooner.
In the meantime, I'm enjoying my D300s. The D7100 didn't tempt me at all. It isn't that I won't want a tad more ISO, a lot more DR and the additional resolution. It is just that those things aren't a good trade for my for the handling, buffer, 10-pin, AF-ON, etc that my D300s has. That's just me.
It has also allowed me to devote my resources to glass. My kit is pretty much done, which is a nice feeling.