This is a tad friendlier to the server

use strict;
use warnings;
use LWP::Simple 'get';
use XML::Simple;
use CPAN;

my $xml = XMLin( get( 'http://perladvent.org/perladvent.rdf' ) );


my $item = shift @{ $xml->{channel}{item} };

CPAN::Shell->install($1) if $item->{title} =~ /-\s(\S+)$/;
[download]

update: and here is the friendliest version possible

use strict;
use warnings;
use LWP::Simple 'get';
use XML::Simple;
use CPAN;

CPAN::Shell->install( 
    XMLin( get( 'http://perladvent.org/perladventone.rdf' ) )
        ->{channel}{item}{title}
);
[download]