Does anyone know for sure if this works?

I don't see it happening... though I have both items at home. I'll give it a shot and report back.

Not gonna happen. The profiles on the Zipp handlebars will not accept the "C" portion of the stem and make it slide onto the clamping area of the bar.

Not going to happen as in you tried it, or you don't THINK it will work?

Tried it in an LBS. They had the big curvy VukaSprint version. The sales rep and I couldn't figure out how to make it work. I don't know about the version of the bars you have though.

The clamp on the stem (the "C" part) is only 24.5 mm wide, just enough to fit the narrow portion on regular round bars.

http://www.competitivecyclist.com/za/CCY?PAGE=BUY_PRODUCT_STANDARD&PRODUCT.ID=11474&MODE=

there's a video link in the second-to-last paragraph, with a how-to. I don't see why it couldn't be placed just next to the clamping area, at the circle-Z logo.

hope this helps.

It also says:

"Note that due to this 260-degree clamp, the C-260 Stem works best with traditionally shaped alloy or carbon fiber bars."

But I know there are exceptions.

The video shows a straight bar from the narrow portion up to larger diameter clamp area, facilitating the sliding of the stem. The stem must be fully inserted onto the bar for the clamp to slide over to the bar's clamping area properly. Try doing that on the Zipp bars. Good luck avoiding marring the clear coat.