I haven't seen James Cameron's Avatar, and nor do I know much about it - or have much interest in it, for that matter. However, I have seen a few blogs where Cameron's inspirations are catalogued, including this one which sees a link with a couple of X Minus One radio shows, including Bradbury's "And The Moon Be Still As Bright".
Thanks to another blog, Chasing Ray, I have been alerted to a new graphic novel by Brian Fies called Whatever Happened To The World Of Tomorrow. It's full of iconography familiar from World's Fairs of the early twentieth century - the kind of Fairs that inspired the young Ray Bradbury. There is a detailed review of the book, with lots of images, on Forbidden Planet's site. Brian Fies is a blogger himself - you can find him here.
Bradbury's own recent connection to graphic novels, Tim Hamilton's adaptation of Fahrenheit 451, gets a mention in "New Books from Old" from Publisher's Weekly.