I've never seen this before but one of my clients has a kitty litter box that you roll onto its side and then onto its top and it dumps the dirty kitty litter into a drawer that you pull out to empty.  No more scooping poop.  It's the best invention I've seen in some time.  It's called "Omega Paw Roll n Clean Litter Box" and seriously, it is awesome.  Listed at $32.99 on Petco.com.  Here's a link that has a picture of it. This link is to the petco.com website which always takes a few seconds to open on my computer. For my kitty clients, I will still scoop poop :) but thought I'd make you aware of this so you wouldn't have to scoop poop. :)