Remove grapes from stem, wash, drain and set aside in large bowl. Combine cream cheese, yogurt, sour cream, sugar and vanilla in a food processor or mix really well, till smooth and creamy. Pour over grapes and mix gently until blended.
Combine brown sugar, granola and nuts in a food processor or chop until well blended. Pour into small bowl and set aside. Sprinkle over the grape mixture. Cover and chill for 2 hr.