I've seen this question around a bit, allowing people to login to the ibays using the ibay name and password as the ftp un and password.
I'm too stuffed to give a step by step guide here, so i'll just give a quick solution..
In the file /etc/e-smith/templates/etc/proftpd.conf/60AnonymousIBay right down the bottom there is a line :
"$OUT .= " DenyAll\n";
this line is in the "limit WRITE" section, which is in the "Directory" section, which is in the "Anonymous /home/e-smith/files/ibays/$key/files" section.
change the Deny part to Allow and people will have write access..
Glen