The SSH part aside you might want to do something like

#!/usr/bin/perl -w

use Net::Ping;
use strict;


my @hosts = qw(www.gellyfish.com petunia.gellyfish.com);

my $ping = Net::Ping->new('icmp');

foreach my $host ( @hosts )
{
     if ( $ping->ping($host) )
     {
       print "$host OK\n";
     }
}
[download]

Now the problem with this is that you need root privileges to use the icmp protocol - you could use udp or tcp instead but this is dependent on the echo service being available on the hosts being checked.