Installing sshpass from Homebrew? Be prepared for this:

$ brew install sshpass
==> Error: No available formula with the name "sshpass" 
==> We won't add sshpass because it makes it too easy for 
==> novice SSH users to ruin SSH's security.

The (security) needs of many outweigh the needs of the few. Normally I find such overbearing policy frustrating, but in this case: good call.