I think that CSS would be greatly helped if we solemnly state that “CSS4 is here!” In this post I’ll try to convince you of my viewpoint.
Of course “CSS4” has no technical meaning whatsoever. All current CSS specifications have their own specific versions ranging from 1 to 4, but CSS as a whole does not have a version, and it doesn’t need one, either.
Then why do it? For the marketing effect.