Vodka can be made from most anything- corn, wheat, potatoes, grapes, maple syrup, honey, molasses, sugar beets, etc. But it is distilled to high proof to remove most flavor, and most of these base materials don't come in a lower distillation proof, unaged form. (Barring corn likker, of course.)
But trying some recent products made me realize there is a closer boundary between pisco and vodka. Pisco 100 is a brand I've written about before that's a very light, sweet, floral pisco. At the SF World Spirits Competition Double Gold Winner tasting event in San Francisco a while back, I sampled Primo Vodka. It is an Argentinian grape-based vodka that comes in Malbec, Cabernet Sauvignon, and Chardonnay varieties. The one I tried is very grapey and flavorful for a vodka.
I think in the near future, we're going to have to address vodkas that not only taste like something, they taste like something with which we're already familiar.