my @lines;
my $line2= Gnome2::Canvas::Item->new ($root,
                'Gnome2::Canvas::Line',  
                points => $points,                      
                fill_color => "red",
                width_units => 8.0,
                join_style => 'miter',
                );
$line2->{'tag'} = 'red', # maybe an array_ref for multiple tags?
push @lines, $line2; 

foreach my $line (@lines){ 
    if( $line->{'tag'} eq 'red' ){print "$line is red\n"} 
  }