In the US, states that have some kind of Breed Specific Legislation in place somewhere include: Colorado, Florida, Illinois, Maine, Minnesota, New Jersey, New York, Oklahoma, Pennsylvania, Texas, and Virginia.
In California, local municipalities are allowed to pass mandatory spay & neuter laws based on breed. However, they are not allowed to pass restrictions or bans based on breed.
In the UK, Pit Bulls are technically banned, but I believe that if you own them, you are required to do multiple things in order to be able to keep the dog, and practically pay an arm and a leg. One obvious thing is that the dog must always be muzzled in public, regardless of whether or not it is properly trained and socialized.
It's actually not just Pit Bull's however. The ban's almost always state "Pit Bull's and Pit Bull-type dogs", and that includes well over 26+ breeds.
Proud American Pit Bull Terrier Owner
Oregon Humane Society Youth Volunteer