In addition to missing binmode, I found a couple of other problems. First, don't forget to close an open filehandle. Second, make sure that everything is initialised. In your script, "publisher" wasn't initialised; also, you were using an unopened filehandle "OUT"---don't do that:). Here's what worked for me:

#!/usr/bin/perl

use strict;
use warnings;
use Encode qw(decode);
use HTTP::Request;
use LWP::UserAgent;
use XML::RAI;

my $ua  = 'LWP::UserAgent'->new;
my $rss = shift @ARGV;

binmode STDOUT,  ":utf8";

open STDERR, '>', 'in.err';
open STDOUT, '>', 'out.log';

my $request = 'HTTP::Request'->new( 'GET', $rss );
print "Requesting...\n";
my $response = $ua->request($request);
print '  Status: ', $response->status_line, "\n";
print '  Last modified: ', $response->header('last-modified'), "\n";
print '  Etag: ',          $response->header('etag'),          "\n\n";

my $response_content = decode( 'UTF-8', $response->content );
my $rai              = 'XML::RAI'->parse_string( $response->content );
my $channel          = $rai->channel;
print "Channel:\n";
print '  Title: ' . $channel->title . "\n";
print '  Link: ' . $channel->link . "\n";
print '  Modified: ' . $channel->modified . "\n";

foreach $_ ( @{ $rai->items; } ) {
    print STDOUT "Item:\n";
    print STDOUT '  Title: ' . $_->title . "\n";
    print STDOUT '  Link: ' . $_->link . "\n";
    print STDOUT '  Description: ' . $_->description . "\n";
    print STDOUT '  Created: ' . $_->created . "\n";
    print STDOUT "------------------------------------------------\n\n
+";
}
$request->header( 'If-Modified-Since', $response->header('last-modifie
+d') );
$request->header( 'If-None-Match',     $response->header('etag') );

close STDERR;
close STDOUT;
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