: As with most power tools, this is another case where the Europeans
: are way ahead of American manufacturers when it comes to design.
: Festool has had riving knives on their circular saws for years:
: http://www.festoolusa.com/products/plunge-cut-circular-saws

Interesting, amd sensible too. Presumably the riving knife travels up and down with the cut depth setting.

The riving blade would be better than the usual spring-driven blade covers on my saws. Those are useless as they are disabled when used with a zero-clearance baseplate - necessary for a clean cut. I plan to add an adjustable stand on the edge of the baseplate so the blade doesn't damage whatever I put it down on; but it isn't much of a problem for me since my cutting table is finished with insulating foam so no harm is done. That gets to be more of a potential problem when working on ply, but I use a miniature circular saw for that these days; it has a neat one-piece baseplate and blade cover design that allows use of a zero-clearance plate. Unfortunately that design is no longer sold.

Problem with most of the Festools I've seen is the price, though.