In colander, toss eggplant with 1/2 tsp of salt ; let stand for 10 minutes. Pat dry with paper towel; set aside. remove casings from sausages; set sausages aside. In large shallow Dutch oven, heat 1 tbsp of the oil over medium-high heat; brown sausages, breaking up with spoon. With slotted spoon, transfer to paper towel-lined plate. Drain fat from pan. Heat remaining oil in same pan over medium heat; cook onion, celery, garlic, oregano, pepper, eggplant and remaining salt, stirring occasionally, for about 15 minutes or until eggplant is very soft. Add tomatoes, breaking up with spoon. Return sausages to pan; bring to boil. Reduce heat and simmer for about 35 minutes or until thickened. Meanwhile, in large pot of boiling salted water, cook pasta for about 8 minutes or until tender but firm. Drain and return to pot or place in serving bowl. Spoon sauce over top.