Two gems spotlighted on gamedev.net.
Sven Forstmann has created a raycast voxel engine, implemented in CUDA. It is a screen space slice renderer, working in planes. It's a significant achievement in so many ways; I recommend you take a look and ponder the implications. It's worth following the notes in his blog.
mtlung has come up with a cool extension to Screen Space Ambient Occlusion (I'll need to update my article soon). In much the same way that old school motion blur is implemented in games using a residual blend of previous frames, Accumulative SSAO retains the samples from previous frames in order to perform integration over time. The clever bit is that the previous samples are re-projected to the current camera position so that the samples travel with camera motion.