Can't believe everything you read on a corporate website. Shocking, I realize...
http://www.twin-pixels.com/software-used-making-of-avatar/
http://www.twin-pixels.com/the-making-of-avatar-some-juicy-details/
Interesting links. Still they do say that the following Adobe products were used:
Adobe After Effects (compositing, real-ime visualizations)
Adobe Illustrator (HUD and screens layout)
Adobe Photoshop (concept art, textures)
Adobe Premiere (proofing, rough compositing with AE)
Avid was used for Video editing.