I used to be able to use the -l option in Samba 2.0/2.2 to set the output log file name to include the machine name -- I log many machines to a single AFS directory. This doesn't appear to work in Samba 3. It looks like the -l option is now just a directory and there is no way for me to include the machine name in the name of the log file.
correct. The current behavior is by default. However, you can use smb.conf variables in the 'log file' directive in smb.conf. e,g, log file = /var/log/samba/%L.log