It's easy to make a white wine from nearly any red grape. The way you do it is crush the grapes, and remove the skins right away. The pigment is all in the skins, and if they are not left with the grape juice during the fermentation process, one will end up with a white wine (actually, a very slight blush wine). How it tastes depends upon how it is vinified - and whether it is finished dry, or slightly sweet (and many of these wines, as well as many roses, are finished to be slightly sweet). If it's slightly sweet, it will taste similar to a white zinfandel, which is basically made the same way - by crushing red zinfandel grapes and removing the skins right away. If it's finished dry, it will usually taste like a cross between a chenin blanc and a dry rose such as a Taval.

In the case of Domaine Carneros, this is the same juice that they make their sparkling blanc de noirs from (which is similar to Champagne, except for where the grapes come from). But, for whatever reason, they've decided to make some of it into still wine rather than bubbly.