20" becomes the new low end, 250 Gig HD, 1 gig Ram (single chip)
23 " New middle of the line, 500 Gig HD,1 gig Ram (single chip), better graphics card
30" Black imac, 500 Gig HD, 2 gig Ram, better graphics card
Same form factor with a few tweaks.
At first I thought, Wuh 30" is far too big. However, since I think you are just copying over the ACD sizes I guess its possible.