1. In a 2- to 3-quart pan, mix grape juice, gelatin, and sugar. Stir over medium heat until gelatin and sugar are dissolved, 3 to 4 minutes.
2. Remove from heat and add wine. Nest pan in a bowl of ice water and stir often until mixture is cold and mounds slightly on a spoon, about 20 minutes.
3. Remove pan from ice water and stir in strawberries and blueberries.
4. Spoon mixture equally into 1- to 1 1/2-cup wineglasses. Chill airtight until gelatin mixture is firm to touch, at least 1 hour or up to 1 day.