Nikon D3S
The Nikon D3S features a redesigned 12.1-megapixel (effective) full frame FX CMOS sensor, with a new Dust Reduction System and a new Hi3 ISO option, which brings the effective ISO range up to 102,400.
Nikon are pitching the D3S as the best camera for low light work, frequently mentioning that the D3S will let you shoot things "your own eyes can't see clearly".
Of course you get that 720p movie mode, at 24fps too, although some might question why there is no Full HD option. Nikon addressed this question in their briefing, responding that the D3S is a professional stills camera and the video should be judged by its quality.
Movies are captured in AVI format, using Motion JPEG, which will only support file sizes of 2GB, which gives you 5 minutes of 720p video. It does have the option to trim start and finish points in-camera, as well as grab a JPEG straight from the movie, although it is only really good for web use or smaller prints (e.g. 6 x 4). You do get full aperture control in movie modes as well as access to the full ISO range, opening up the possibilities for low light filming.
Various other tweaks have been made, including some minor changes to buttons and the battery to make it easier for gloved hands, responding to customer feedback. You also get 100% viewfinder coverage in FX shooting mode.
There is a new NEF RAW image editing system built-in, which is designed to enable you to tweak an image and extract the JPEG you want, so you can send it straight out for publishing or print directly from the camera.