>Any suggestions on getting ssh to allow logins without a password? I.e.
>host-based authentification. I've tried the standard stuff but it
>didn't work. Any similar experiences? (This is needed for a cluster.)

Just forget about .rhosts and the like, passwords cans be caught on the network.

The solution :
generate a pair of keys local with
ssh-keygen -t dsa
(CAUTION : specify a non empty passphrase (ako password associated with the pair))
copy the contents of .ssh/id_dsa.pub into .ssh/authorized_keys2 in the distant (or even localhost) machines' users home directories (CAUTION : one such key per line, remove end of lines if you copy/paste from a terminal window)
launch ssh-agent locally (will ask you the passphrase)
do ssh-add to add your identity to the local agent

Any subsequent ssh, scp or sftp command will work unattended, ssh-agent doing all the negociation work for you.

Very useful will cron tasks, too !