But nonetheless, thats how you can setup a password less login to another host from OS X:
# Generate your local public/private key (if not already done)
# (you can press enter to accept the defaults)
# Create the remote directory (especially for Windows hosts)
ssh firstname.lastname@example.org mkdir "~/.ssh/"
# Copy the public key to your remote host
scp .ssh/id_rsa.pub email@example.com:"~/.ssh/"
# Add it to the authorized_keys File
ssh firstname.lastname@example.org "cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys"
And your done!