gistfile1.pl

#!/usr/local/bin/perl --

use strict;
use warnings;

use JSON::Syck;
use LWP::UserAgent;

my $agent = LWP::UserAgent->new;
my $a = shift or die;
my $b = shift or die;
my $c = $agent->get(sprintf qq#http://twitter.com/users/show/%s.json#, $a);
my $d = $agent->get(sprintf qq#http://twitter.com/users/show/%s.json#, $b);

if ( $c->is_success and $d->is_success ) {
   my $e = JSON::Syck::Load($c->content);
   my $f = JSON::Syck::Load($d->content);

   die if $e->{protected} or $f->{protected};

   my $g = $agent->get(sprintf qq#http://twitter.com/friends/ids/%s.json#, $f->{screen_name});
   my @h = @{ JSON::Syck::Load($g->content) };

   if ( grep { int $e->{id} == int $_ } @h ) {
      printf qq#%s is followed by %s\n#, $e->{screen_name}, $f->{screen_name};
   }
}

exit;