http://www.computerandvideogames.com/news/news_story.php?id=116287
In Project Gotham Racing, there's a Paris race track right? Several tracks cut through the city of Paris. Imagine that the next version of Gotham just sets up the city of Paris, and now you can drive through however you want and boom, you've created your own track. There's a little track editor but the track editor is just a drive through town. You can do that on a console, the next-generation Xbox can do that very well, but then you say "I want it to look like my Paris" and I want to paint the Eiffel tower purple and I want to put my name on a storefront, maybe I want to do some customised billboards.
A console is a bad place to do that. But now you can go over into a PC space and maybe you can refine the track a little, change the colour of the Eiffel tower, modify your billboards or whatever and that gets reflected back to the console environment.