The SimpleDRM driver is the new name for his simple/generic DRM graphics driver. The driver was formerly known as the DVBE driver in his first version but renamed it as SimpleDRM, isnce it's supposed to be the most basic Direct Rendering Manager driver. SimpleDRM is similar to efifb.c, vesafb.c, offb.c, simplefb.c, and other simple graphics display drivers within the kernel.
The SimpleDRM driver only provides a single virtual CRTC+encoder+connector combination and allows user-space drivers to create one "dumb buffer" at a time and to attach it to this driver that's in compliant with the DRM/KMS APIs.
Overall, it's an interesting concept and his latest code can be currently found on the kernel mailing list and will hopefully be merged into an upcoming Linux kernel release.
Beyond David's VT killing endeavor, he also has an interesting Linux graphics summer project too.