Heat 1/4 cup olive oil in heavy large skillet over medium-high heat. Add sliced leeks and sauté until golden and tender, about 10 minutes. Add sliced zucchini and sauté until beginning to soften, about 3 minutes. Add 1 cup half and half and crumbled goat cheese and stir until goat cheese melts. Remove sauce from heat. Season sauce with salt and generous amount of pepper.
Meanwhile, cook fettuccine in large pot of rapidly boiling salted water until pasta is just tender.
Drain fettuccine and return to pot. Add sauce to fettuccine and toss until thoroughly coated. Transfer fettuccine to large bowl. Top pasta with smoked salmon and serve immediately.