I love the Jamba Juice Orange Dream Machine smoothie. It tastes like dreamsicle. However, they are expensive and frankly, quite unhealthy.
Even the new prepackaged mixes at the store aren't much better.
Here is a taste alike recipe with a with a lot healthier ingredients you can whip up at home with just a blender.
2 scoops fat free orange sherbet
2 scoops fat free frozen vanilla yogurt (look near the frozen fruit at the store)
1/2 cup skim or soy milk
1/2 cup orange juice
1/2 cup ice
1 tsp sugar (if desired)
Blend. That's it.