The ssh man page says:
    ssh exits with the exit status of the remote command or with 255 if an error
occurred.

On my Fedora 8 install (openssh-4.7p1-4.fc8), it doesn't matter whether the
remote command succeeds or fails, the exit status is always 0.

$ ssh localhost true
$ echo $?
0

$ ssh localhost false
$ echo $?
0

The expected result is that "ssh localhost false" returns an exit status of 1.

My CentOS 5 install has openssh-4.3p2-24.el5 and it works fine.

I've tried as myself and as root, in case my own shell configuration is the
cause, but I get the same result.