Put the blueberries and sugar in a small saucepan, stir to mix, and bring
to a boil over medium heat. Reduce heat and simmer, stirring occasionally,
until the berries are very tender and the sauce is slightly thickened,
about 8 minutes. Remove from the heat, and let cool. Refrigerate until
cold before using.
For the ice cream:
Blend all the ingredients until mixture is smooth and sugar has dissolved.
Chill until very cold, overnight if possible. Freeze mixture in ice cream
maker. Transfer to an airtight container, drizzling in the blueberry sauce
intermittently. Place in freezer until firm.