Cook the orzo al dente in salted water. Drain well. Return to pot and add the butter, mix well to coat all the pasta.
Butter an 11 x 7 Pyrex dish.
Mince the dill and basil.
Heat olive oil in a large skillet over medium high heat. Add garlic and sauté just until translucent. Add the tomatoes, dill and basil. Cook until the tomatoes are slightly soft, about 10 minutes. Add the shrimp and cook, stirring occasionally, just until pink about 3 or 4 minutes. Remove from heat.
Preheat oven to 500°F.
While the tomato mixture is cooking, mince the oregano (or crush the dried with your fingers). Crumble feta into a small bowl. Add the oregano and toss with feta until blended.
Spread the orzo evenly in the buttered baking dish, top with the tomato shrimp mixture, then put the feta oregano on top.
Bake just until feta begins to melt, about 5 minutes.