I don't really know how many public IPV6 ftp servers there're on the world, i was talking about two sources: SmartFTP's knowledge base and the IPV6 group (if the info of those sites is outdated or incorrect flame them
).
I know that IPv6
will be the next big 'boost' of the Internet but i consider that's very soon to start demanding IPV6 FTP clients, due to the extremly low number of public IPV6 FTP servers around the world and the fact that (if i'm not wrong) most of the connections to those servers are through IPv4 to IPv6 tunneling (there are even a lower number of people that have real IPv6 addresses asigned by an ISP).