Update April 25, 2011: A Nevada bill, Assembly Bill (A.B.) 324 would have prohibited any local government from passing an ordinance that would deem a dog "dangerous" or "vicious" based "solely on the breed of the dog". The bill would also have prohibited law enforcement from deciding a dog is dangerous "solely based on breed".
Unfortunately, the bill at least as is, won’t be considered further this session; a rule states a final vote by the Assembly on a bill must be taken before the 80th day of the legislative session. That didn’t happen. Nothing is over until the session ends, however; the session ends June 6.