Not too long ago I ran into the same problem, and the only place I found a solution was pVoice and pStory. It's probably documented somewhere, but I couldn't find it at the moment (in my perl Tk documentation; it's prolly documented in the c or whatever other lang Tk is available originally in). It turns out, that when you specify a -data string, it has to be base64 encoded, and that is why the following works;

#!/usr/bin/perl -w
$^W=1;
use strict;
use Tk;
use Tk::JPEG;
use MIME::Base64 qw( encode_base64 );

my $fname = "rock.jpg";
open(F, $fname) or die "cant open $fname";
binmode(F);
undef $/;
my $jpeg = <F>;
close(F);

my $win = new MainWindow;
my $image = $win->Photo( -data => encode_base64($jpeg),
                         -format => 'JPEG',
                       ,);
$win->Label(-image=>$image)->pack;

MainLoop;
[download]

I gotta say is thanks Jouke, no wonder you got that perl GUI book deal.

update: after some "testing" :D, it turns out you don't really need to specify -format, as it will pick it up from the -data.

 
___crazyinsomniac_______________________________________
Disclaimer: Don't blame. It came from inside the void
perl -e "$q=$_;map({chr unpack qq;H*;,$_}split(q;;,q*H*));print;$q/$q;"