I’ve run into this before–my school’s web space is only accessible via FTP with TLS/SSL, and the problem is that I don’t know of (and I can’t find) a Linux client that lets me do that. I wasted about 5 minutes trying to find something I could apt-get, but ended up downloading FileZilla and running it in Wine (I also tried three versions of CuteFTP, all of which failed to run properly).
Update 12/11/2006: See if this works.