I am experiencing this problem with 9.04. I noticed it while trying to get PXE boot working.
In my case altering the line in inetd.conf doesn't solve the problem.
tftp dgram udp4 wait root /usr/sbin/in.tftpd /usr/sbin/in.tftpd -s /var/lib/tftpboot
and tftpd never starts. I restart xinetd and get an OK status message, but I don't get a connection and netstat -a doesn't show anything listening.
If I run tftpd standalone via
/usr/sbin/in.tftpd -Ls /var/lib/tftpboot
it shows as running in IP v4.