Zune is going to be discontinued. If you want to pick one up while you still have the option, do so now. By the time the Zune HD goes on sale on September 15th most of the older models will be out of stock, and unavailable forever more. I think resting everything on the Zune HD's success or failure is actually a pretty clever move by Microsoft. If this device succeeds, the Zune has a future. If it doesn't, at least Microsoft can cut their losses without dumping more devices.
You can only get the black body if you order a Zune HD 16 GB version. The 32 GB version only comes in platinum. If you want different color options for either, you'll have to wait until September 15th. If you place your order on Zune Originals, you'll even be able to customize your device with additional color options or etchings.