If you want to loop over your hashes, you can use references:

for( \%a, \%b, \%c ){
   print sort keys %$_, "\n"; 
}
[download]

You can mix all hashes in one
(See above, toolic's node)

#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my $a = { 1 => 'a', 2 => 'b', 3 => 'c' };
my $b = { 1 => 'd', 2 => 'e', 3 => 'f' };
my $c = { 1 => 'g', 2 => 'h', 3 => 'i' };

my $abc;

for my $h_ref ( $a, $b, $c ){
    for my $key (keys %$a){
        push @{ $abc->{$key} }, $h_ref->{$key};
    }   
}

print Dumper $abc;

__END__

$VAR1 = {
          '1' => [
                   'a',
                   'd',
                   'g'
                 ],
          '3' => [
                   'c',
                   'f',
                   'i'
                 ],
          '2' => [
                   'b',
                   'e',
                   'h'
                 ]
        };
[download]

hth,
PooLpi