# Open connections
for my $server (@targets) {
   $ssh{$server} = new Net::OpenSSH($server, ...);
}

# Do stuff in parallel
for my $server (@targets) {
   my $pid = fork();
   if ($pid) {
      $pid{$server} = $pid;
   } else {
      # In child process. Do stuff
      $ssh{$server}->system( stuff );
      ...
      exit 0;
   }
}
waitpid($pid{$_}) for @targets;

# Do more stuff ...
for my $server (@targets) {
   $ssh->system (more stuff);
}