Rotten Tomatoes has interviewed Brad Bird briefly about taking over Ratatouille and what kind of changes he made and what he kept the same. He even mentions, without naming it, 1906.
If you are interested, take a read here.
Last modified: October 27, 2007
Thanks for the link. It seems like Jan did most of the character & scene design and the general plot, but Brad, in a short time (and with no focus groups as he said) made the whole thing more interesting. Cool!