From the manufacturer's official website:

Given their great success in 2006, Campagnolo® decided to offer a new version of the Vento™ G3™6, the Black.
The Vento™ Black keeps all the features which made it popular: G3™ spoking with variable-section spokes, dynamic balancing, special oversize hubs, front hub with track-style oversize flanges, and monolithic freewheel body, but also becomes available with the new finish to make great chromatic combinations possible with a greater number of frames.

Of course Vento™ G3™ wheels continue to be available in the splendid Silver finish with which they debuted.

For more information, please visit this product's webpage.