The new gym is really well lit for a high school facility, but when shooting volleyball with my Nikon D300 I still ended up with either lots of low-light, high-noise artifacts and/or slightly blurry shots due to having to use a slow shutter speed. This was shooting at ISO 2000, shutter around 1/250 and either 70-200/f2.8 or 50/f1.8 glass.
I was really looking forward to trying out the the new Nikon D700 for the basketball games and it was almost as good as I expected. The D700 uses the same sensor as Nikon's $5000 D3 at a much better price point. I was able to shoot at ISO 2500-5000, shutter around 1/400 to 1/500 using my 70-200/f2.8 zoom. Auto-focus acquisition was a bit slower than expected, probably due to the limited light coming through the 70-200.
The nice thing was my ability to get much sharper images than with volleyball, though even this camera isn't a miracle worker at ISO 5000, so some noise does start to show on the web images, though prints are a bit more forgiving. I'll probably limit myself to ISO 3200 next time and see how that works.
It's a somewhat interesting problem. A good photo needs a clean background so I tend to shoot from a low position, but the gym lights are very bright when shooting upward, while the players often create their own shadow. Sometimes the camera just can't get it right and I spend way too much time post-processing the images before posting them for sale. ;-)
I'd love to be able to set up lights in the gym, which mitigates the somewhat flat look you can get with low-light, high-ISO, images, but I don't see that happening anytime soon, so I'll continue to enjoy shooting the D700 and hopefully even improve on some of these enjoyable images.
Everyone have a safe New Years and feel free to say hi if you see a tall guy with grey hair wandering around the court with a camera or two (or on the sidelines of the soccer field, as the one sport I was actually competitive in starts in January. ;-)