Check this out:
http://www.nyc.gov/html/doh/download...article161.pdf
No grandfathering provision as far as I know. The list is not thought out well. It bans all members of Iguanidae. That's aimed at the green iguana, but includes anoles too! All monitors and pythons are banned, despite the fantastic small types of both. Oh, you can't have an elephant or a whale either. Yes, they are specifically on the list.
-Larry in NYC