I only spent a few minutes playing with the D7000 at tonight's game. Here are a couple of shots:
Straight out of the camera -- just resized and a bit of sharpening post-resize: D7000, ISO 6400, High ISO noise reduction = Normal Sigma 120-300 f/2.8 @ 220 mm, f/2.8, 1/640
A shot cropped and processed with Noise Ninja and curve and vibrance adjustment in Photoshop: D7000, ISO 6400, High ISO noise reduction = Normal Sigma 120-300 f/2.8 @ 300 mm, f/2.8, 1/500
A 100% crop straight out of the camera of the above.
All in all, I felt it performed pretty well. Autofocus was pretty good. My sense was that AF was pretty close to what the D3 does, but I wasn't using the same lens on the two bodies so that's only a preliminary feeling. I'll have to use it much more to really say much with certainty. Auto WB was also quite good.
Despite what I've read elsewhere, the noise performance is not quite up to D700/D3 standards. It's pretty darn good, though. I'd happily make 8x10 prints from the ISO 6400 shots. With a little Photoshop TLC, I think serviceable 12x18's would be doable.