drftpd - Distributed FTP Daemon (Score 1)

This sounds a bit similair to drftpd, Distributed FTP Daemon. Although drftpd does not stripe data at the protocol level, you can use some kind of splitting tool such as RAR with multiple archives to stripe data across nodes. I'd implement striping at protocol level but that would break site-to-site FTP transfers and would require improved protocol and FTP clients. GridFTP might be better for it anyway.