Spent some time looking into HDRI and mental ray, I pretty much knew how to set it up since before, got a little refresher and learned some new techniques I we're not aware of.

Good links on the topic:

http://www.debevec.org/
http://www.learning-maya.com/ HDRI search
http://www.digitaltutors.com/digital_tutors/index.php

Another good resource:
http://www.neilblevins.com/cg_education/cg_education.htm