"While SIGGRAPH is usually thought of as strictly a SIG for computer graphics, the organization also claims interest in interface/interaction design. To that end this talk will draw from psychological research and almost two decades of interactive media (games especially) to review fundamental principles for the design of engaging and appealing applications and presentations."
The PowerPoint presentation is available for online viewing.
Additionally, you can find a more recent set of HTML pages from this talk by Tim, with a lot more content, at http://www.designhappy.com/.