my %new2 =
hmap { $_[1]{nick} =~ /rbush|fred/ ?
      ($_[0], hmap { $_[0], $_[1] } %{$_[1]}) : () } %$h;

##</code><code>##

my %new2 =
hmap { $_[1]{nick} =~ /rbush|fred/
          ? $_[0] => { hmap { $_[0], $_[1] } %{$_[1]} }
          : ()
     } %$h;

##</code><code>##

sub hmap (&$)
{
    my $code = shift;
    my @i = %{ shift() };
    my @rv;
    push @rv, $code->(shift @i,shift @i) while @i;
    return { @rv };
}

my $new2 =
hmap { $_[1]{nick} =~ /rbush|fred/
          ? $_[0] => hmap { $_[0], $_[1] } $_[1]
          : ()
     } $h;