#1: ATI graphics cards are now also fully supported
#2: Introduction of city layer editing functionalities
#3: Several minor improvements such as 100x faster street growth
This is a must read for anyone interested in games development as it offers a very detailed insight in the step-by-step development of a top modern gaming title ranging from initial storyboarding to the role of the programmers in the modelling/animation of the game assets.
Tons of images featured in there too which make the description of the processes even more insightful. Easily one of the best features I've seen in this area, check it out at the official XSI site, found at the link below, if only more game developers bothered to do 'making ofs' of this calibre!