I had a girls-day-out last weekend at South Coast Plaza and stop #1 was the MAC Pro Store where I decided to pick up some of the Sculpting & Shaping Powders. I already had the Accentuate/Sculpt Duo that was released back in December of 2007. I've actually neglected this duo because I normally don't like split-colored powders - but I pulled this out recently and really like it for natural contouring and highlighting the eyes.
The Shaping Powders are the lighter colors with subtle pearl powders for a very subtle glow. The shimmer is very soft which is nice and is more natural than the MSF highlighter powder I've tried. Think along the lines of Chanel's Poudre Douces but not quite as subtle and I wouldn't recommend them for the entire face.
The Sculpting Powders are the matte darker colors that come in various shades of beige and brown. These are meant to be used for contouring to create shadow-like effects.
MAC has repromoted their Sculpt/Shape Duos for several collections since the original release, so if you missed out on the previous releases, there's a chance they might repromote it again in the future. If you're near a Pro Store and like natural beige/brown/flesh toned powders, I recommend you try and check these out!