Put rhubarb, sugar, and 2 tablespoons water into a medium saucepan. Cover, and bring to a simmer over medium-high heat. Reduce heat to medium-low. Stir once, and cook, uncovered, until rhubarb has completely softened, about 8 minutes. Let cool slightly.
Transfer rhubarb mixture to a food processor, and puree until smooth. Transfer to a small bowl. Refrigerate rhubarb puree until cool, about 30 minutes.
Beat cream with an electric mixer or by hand until soft peaks form. Gently fold rhubarb puree into the whipped cream in 2 batches, leaving some streaks remaining. Spoon into glasses.