i am also excited because southern island (gcn) is amd's first original gpu architecture afaik.
haven't heard about gddr6 but heard that xdr2 is much more powerful and more power efficient than gddr5.
rambus is a massive troll ofc but if they make a performance-power-price effective ram, then why not use it.
and the new high end gpus are rumored to use 384 bit bus, means more memory bandwitdh for high res gaming with eyecandies turned up to 15!
imo amd already has the highest performing (abd the most power efficient) 256-bit bus gfx cards in the market today - the radeon hd 6970 and the dual gpu 6990. with the new 384-bit cards, they'll only get better!