The Nikon D4 has the ability to monitor and control the camera via a web browser on a portable device like the iPad.
Nikon chose the HTTP protocol to do this, which is the same data protocol that websites use. With a WIFI or internet connection you can control the Nikon D4 through Safari on your iPad, iPhone or Mac, indeed any other personal computing device with a web browser.
Although it probably won't give you the frame rate, latency and picture quality to make critical judgements it is an interesting feature and something which could be built on in future. For controlling the camera remotely it is certainly interesting, say making exposure and setting adjustments from within a vehicle when the camera is attached to a crane or the top of a car.
It is more a time saving / convenience thing than a replacement for a field monitor, really.
There has been a limited amount of footage released onto the internet today from the Nikon D4. Nothing all that impressive and the samples videos are heavily compressed (bit silly!) but there are no signs of any aliasing or moire. To judge the camera properly we'll have to wait a big longer I think.
From Nikon, here are the main video features of the D4: