This is your code, with minimal modifications and File::Find::find that handles the recursive search for mp3s. :)

#!/usr/bin/perl -w

use strict;               
use MP3::Tag;
use File::Find;

# define how autoinfo tries to get information
# default:
# MP3::Tag->config("autoinfo","ID3v2","ID3v1","filename");
# don't use ID3v2:
# MP3::Tag->config("autoinfo","ID3v1","filename");

# read a directory path from STDIN
# Since we don't have a prompt, the cursor is just going to sit idle u
+ntil your supply some input
while (<STDIN>) {
    chomp;
    # find all entries in the given directory/folder, calls the &wante
+d call-back for every file/directory encountered
    find(\&wanted, $_);
}

sub wanted {
     # $_ automatically contains the current file name i.e. "Knock You
+ Down.MP3"
     # don't bother processing anything that does not have the .mp3 ex
+tension, case irrelevant
     return unless /mp3$/i;

    if (my $mp3=MP3::Tag->new($_)) {
        print "$_ (Tags: ", join(", ",$mp3->get_tags),")\n";
        my @info=$mp3->autoinfo;
        print "* Song: $info[0]\n";
        print "* Track: $info[1]\n";
        print "* Artist: $info[2]\n";
        print "* Album: $info[3]\n";
        print "* Comment: $info[4]\n";
    }
    print "\n";
}
[download]

This works on my Strawberry Perl 5.12.3 on Windows 7. If it works here, it should work anyway.