Hmmm... I think I'd want to do that in something with a lid. Alcohol doesn't freeze very well. I tried making some "adult" popsicles one summer as a treat. I may have been using something stronger than a typical wine, but I also had mixed it heavily with fruit and juice, but it turned out more of a slushy than a popsicle. That said, my house does tend to have left-over wine. Visitors sometimes bring wine and it's another thing with sulfites that I need to avoid. A bit added to a sauce would be fine though or a marinade, which I tend to use more than sauces.
I remember Deliah Smith recommending left over wine frozen in cubes, to be used later in stocks or sauces.
Rita Bliden wrote:We freeze leftover coffee, and tomato paste. We sometimes buy the paste in a tube, but it's much less expensive in the can. I like the pesto idea, as well as the salsa.