Nope I just checked today. If you get lunch it includes a dessert, but not dinner
Not sure where you got that there is no dessert but this is taken straight off the Disney 2013 Dining plan from the website.
Disney Dining Plan
With your Disney Dining Plan, for each night of your package, each Guest in your party (ages 3 and up) receives:
1 Table-Service Meal
Each (adult or child) table-service meal includes:
1 entrée
1 dessert (lunch and dinner only)
1 single-serving, non-alcoholic beverage
Or
1 full buffet
1 Quick-Service Meal
Each quick-service meal includes:
1 entrée or 1 complete combo meal
1 dessert (lunch and dinner only)
1 single-serving, non-alcoholic beverage
1 Snack
Examples of snacks are:
1 frozen ice cream novelty, popsicle, fruit bar, popcorn scoop (single-serving box), single-serving bag of snacks, single piece of whole fruit, 20-oz. bottle of Coke, Diet Coke, Sprite or Dasani water, 22-oz. fountain soft drink or juice, 12-oz. coffee, hot chocolate or hot tea, single-serving prepackaged milk or juice
Children ages 3-9 must order from a Children's Menu where available. Plan must be purchased for entire length of stay and for the entire party (ages 3+). Meals are non-transferable between party members and expire at midnight on day of check-out.
1 Resort-Refillable Drink Mug Per Person
Bring your Resort mug to any quick-service restaurant at your Disney Resort hotel and refill it as often as you like!