The documentation makes it sound like the following code would work (using RSA Authentication).

    $ssh->login([ $user [, $password ] ])

     Sets the username and password to be used when
     authenticating with the sshd daemon. The username $user is
     required for all authentication protocols (to identify
     yourself to the remote server), but if you don't supply it
     the username of the user executing the program is used.

     The password $password is needed only for password
     authentication (it's not used for passphrases on encrypted
     RSA/DSA identity files, though perhaps it should be). And if
     you're running in an interactive session and you've not
     provided a password, you'll be prompted for one.
[download]

use Net::SSH::Perl;
$ssh = Net::SSH::Perl->new('localhost', debug=>1);
$ssh->login() or die "login fail!\n";
($i,$j,$k) = $ssh->cmd('ls | wc -l');
print "$i\n";
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It doesn't.

localhost.localdomain: Reading configuration data /home/MYUSERNAME/.ss
+h/config
localhost.localdomain: Reading configuration data /etc/ssh_config
localhost.localdomain: Connecting to localhost, port 22.
localhost.localdomain: Remote protocol version 1.5, remote software ve
+rsion 1.2.32
localhost.localdomain: Net::SSH::Perl Version 1.23, protocol version 1
+.5.
localhost.localdomain: No compat match: 1.2.32.
localhost.localdomain: Connection established.
login fail!
[download]

However, if I explicitly give MYUSERNAME and a FAKE password...

$ssh->login('MYUSERNAME','FAKEPASS') or die "login fail!\n";

localhost.localdomain: Reading configuration data /home/MYUSERNAME/.ss
+h/config
localhost.localdomain: Reading configuration data /etc/ssh_config
localhost.localdomain: Connecting to localhost, port 22.
localhost.localdomain: Remote protocol version 1.5, remote software ve
+rsion 1.2.32
localhost.localdomain: Net::SSH::Perl Version 1.23, protocol version 1
+.5.
localhost.localdomain: No compat match: 1.2.32.
localhost.localdomain: Connection established.
localhost.localdomain: Waiting for server public key.
localhost.localdomain: Received server public key (768 bits) and host 
+key (1024 bits).
localhost.localdomain: Host 'localhost' is known and matches the host 
+key.
localhost.localdomain: Encryption type: DES3
localhost.localdomain: Sent encrypted session key.
localhost.localdomain: Received encryption confirmation.
localhost.localdomain: Trying rhosts authentication.
localhost.localdomain: Trying rhosts or /etc/hosts.equiv with RSA host
+ authentication.
localhost.localdomain: Rhosts with RSA authentication failed: Can't lo
+ad private host key.
localhost.localdomain: Trying RSA authentication with key 'MYUSERNAME@
+localhost.localdomain'
localhost.localdomain: Received RSA challenge from server.
localhost.localdomain: Sending response to host key RSA challenge.
localhost.localdomain: RSA authentication accepted by server.
localhost.localdomain: Sending command: ls | wc -l
localhost.localdomain: Entering interactive session.
     127
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Anybody else run into this sorta thing?