Michael here. In case you still harbored any doubts that the CG characters in James Cameron's Avatar will be anything less 100% photorealistic (i.e. indistinguishable from reality), this video demo of the Image Metrics facial performance capture technology that Cameron is using should make you a believer.
"Image Metrics’ revolutionary technologies for performance-driven character animation require neither complex motion-capture hardware, nor specialist technical knowledge. Their animation solutions put the performer at the heart of the process, dramatically enhancing the creativity and reducing post-production time. It is this type of innovation that will again allow us to present to the consumer, stories that could not otherwise be told."