The new white paper, titled Mac Pro Technology Overview, is chock full of detail, well worth going through if you own, or are considering a Mac Pro.
The paper is pretty long (45 pages), so if you are interested in the new AMD modules, open the PDF and do a find for AMD, which should take you to the description of the Radeon Pro 580X MPX Module.
Also worth checking out is AMD’s Mac Pro-centric web page covering their new graphics cards.