my %hash = map { my $item = pop @$_; map { $_, $item } @$_ }
 [
  ( 'key1', 'key2', 'key3' ) =>
    'Value for key1, key2, and key3'
 ],
 [
  qw( key4 key5 key6 ) =>
    'Value for key4, key5, key6'
 ],
 [
  ( 'key7', 'key8', 'key9' ) =>
    'Value for key7, key8, key9'
 ];

# So we can now do the following. Hopefully everyone
# now understands what the hash declaration above does
# Output shown after __END__
while ( my($k,$v) = each %hash ) {
  print "$k: $v\n";
}

__END__
key1: Value for key1, key2, key3
key2: Value for key1, key2, key3
key3: Value for key1, key2, key3
key4: Value for key4, key5, key6
key5: Value for key4, key5, key6
etc etc etc