I won't know how it turns out for another 4 weeks or so, but here's what's going on so far:
Take 2 cups of cranberries, mix with 1 cup of sugar. Put in sauce pan and add about 1/4 cup of water. Simmer until berries start to soften and sugar starts to dissolve.
Scoop into mason jar, fill with vodka and shake. Then store in a cool dark place. Shake every day or so for the first week.
In 4 weeks you should have delicious cranberry vodka!
edited 1/4/12 : This vodka seems to taste best 4-6 months after making. It was still very bitter after 4 weeks.