Actually, this has been around for at least five years that I know of. Saw this demo a long time ago. I have been wondering when it would catch on. Originally, I was to understand that practically the whole mechanism had to be replaced after a "save" - which at the time was $700-$800. The cost of the saw was only around $1,000. This may have changed since then.
Regardless - this is great technology. I wonder if it could be adapted to portable saws, drills, trimmers, etc.
I understand the inventor just won a large ($25 mill) patent infringement cases against one of the larger BOX stores becasue they copied (or had copied) it and were selling it.
Hope he gets his money and continues to improve the idea.