Here's a random image of the physics stress test, featuring lots of boxes falling on rotating platforms (the red platforms are attached in place by axles, and thats the FPS counter in the bottom left corner).
And another from a benchmark, with 50 cubes and 50 spheres with 10000 quads each. About half of them are transparent.
I'm probably going to implement tasks for Spineless in two phases. First, I will just create simple tasks which will be updated each frame. Later, I will create new tasks classes using Stackless, greenlets or the enhanced yield statement in Python 2.5. They can happily live together, or at least should be, and there's no point in making them directly replaceable with each other.