Combine cranberry sauce and vodka in large airtight container. Store in freezer for at least 3 days. Give it a good shake any time you open the freezer.
Chill 8 martini glasses in the freezer.
Strain the solids using a fine mesh strainer. To serve, pour the ice cold cranberry vodka into each of the 8 frozen martini glasses. If not immediately serving, store the strained liquid in the freezer until ready to serve, and give it a shake before pouring into glasses.
If desired, spray fresh cranberries with a bit of water and then roll in sugar. Serve on a skewer over the glass.