In a small saucepan, stir together the sugar and unflavored gelatin. Stir in cranberry juice concentrate. Heat over low heat just until sugar and gelatin dissolve. Transfer mixture to a small bowl; cover and chill for 1 hour or until mixture is thickened.
Meanwhile, in another small bowl, combine lime juice and cranberries. Let stand for 10 minutes. Do not drain.
In a large chilled mixing bowl, beat whipping cream with an electric mixer on medium speed until soft peaks form (tips curl). Gently fold in chilled gelatin mixture, dried cranberry mixture, and the 1 teaspoon lime peel. Divide evenly among small shot or cordial glasses. Chill mixture in glasses at least 30 minutes or up to 24 hours before serving. If desired, garnish with additional lime peel.