Eye-Tracking Studies: Usability Holy Grail?
http://experiencedynamics.blogs.com/site_search_usability/2004/12/eyetracking_stu.html

Spillers, Frank
Demystifying Usability
2004

Abstract:

The reality is that eye-tracking, while valuable, doesn't make usability testing any more powerful. It's what you do with the observations and the usability test data that counts.