Sung Meister mentioned Mark Miller. You can find some of his blog posts regarding great UI on the Developer express blog. Here's a screencast of his Science of great UI presentation: part1 and part2. (both require Veoh player).
You can also find him on dnrTV: Science of great user experience: part1 and part2.
Here's a google techtalks about user experience by Jen Fitzpatrick.
Cheers
