Here is a quick list of interesting Siggraph 2011 courses and talks available online.

Courses/Talks :
Advances in Real-Time Rendering in Games
Beyond Programmable Shading
State-of-the-Art:  Interactive Global Illumination
Destruction and Dynamics for Film and Game Production
Filtering Approaches for Real-Time Anti-Aliasing
Production Volume Rendering
Compiler Technology for Rendering
Liquid Simulation with mesh-based Surface Tracking

NVIDIA Slides , Videos

OpenGL/OpenCL :
OpenGL BOF Slides
Introduction to Modern OpenGL Programming
OpenCL BOF Slides

HPG 2011

Also a great list with more posters and talks is available on Stephen Hill's Blog
There is also my talk on Interactive Indirect Illumination Using Voxel Cone Tracing :-)