For the Lemon Vinaigrette:
Cook the couscous. Fluff with a fork and set aside to cool.
Heat the grill to 375 degrees F. Toss the shrimp with olive oil, place them in a grill basket, and grill on each side for two to three minutes, or until the shrimp have turned pink and are firm to the touch.
Sauté the arugula in a little olive oil until tender, two to three minutes.
Toss together the couscous, shrimp, arugula, and Lemon Vinaigrette. Add salt and pepper to taste. Garnish with lemon zest.
Purée all of the ingredients except the olive oil in a food processor or blender. While the processor or blender is running, slowly add olive oil and blend until emulsified. The vinaigrette can be made and refrigerated several days in advance.