Please keep in mind this opengl renderer for the cell processor is a *software* renderer, not a *hardware* renderer. In other words, all of the rendering will be done by the processor, which is NOT specifically designed for graphics computation like a GPU is.
With this software renderer, things like the xgl/compiz effects might work okay. Maybe even an opengl accelerated SNES emulator. But until access is granted to the RSX, there is no hope in a playable PS2 or Dreamcast emulator. Even then, it is unlikely.