What they are is "inverted suspension forks". I cannot speak to them being lighter, but just looking at them you can see they would be less flimsy. In a normal suspension fork you have a crown where the tops of the fork ane pressed/welded into the crown. This creates a weak spot right at the top of the fork. In these that area is solid, and thus much stronger. I believe there is also an improvement in handling, but I have no data on that.
That's the RS-1 or the Rockshox RS1. it's a 29er only XC fork. Yeah It's light and all and the idea of the an inverted profile is for added stiffness and whatnot. Although there are reports about its stiffness not living up to the hype. It's expensive too.