I solved it- after I sent the post I realized I had encoded in 64, and did it again! DOH; regardless it works now! Here's the code for all to see:

#!/usr/bin/perl -slw

# Origional:
# Test program to decode the multipart-replace stream that
# ZoneMinder sends.  It's a hack for this stream only though
# and could be easily improved.  For example we ignore the
# Content-Length.
#
# Mark J Cox, mark@awe.com, February 2006
#
# Added onto by Russ Handorf to support multiple "monitors"
# Russ Handorf, rhandorf@handorf.org, April 2006 
# Thanks to BrowserUK and perlmonks for the wonderous teachings of thr
+eads!

use Tk;
use Tk::JPEG;
use LWP::UserAgent;
use MIME::Base64;
use IO::Socket;
use threads;
use threads::shared;

my $host = 'enter an ip';
my @urls = qw[ /cgi-bin/nph-zms?mode=jpeg&monitor=1&scale=100&maxfps=5
+&user=web&pass=webuser /cgi-bin/nph-zms?mode=jpeg&monitor=2&scale=100
+&maxfps=5&user=web&pass=webuser /cgi-bin/nph-zms?mode=jpeg&monitor=3&
+scale=100&maxfps=5&user=web&pass=webuser /cgi-bin/nph-zms?mode=jpeg&m
+onitor=4&scale=100&maxfps=5&user=web&pass=webuser ];

my @data  :shared = ('') x 4;   ## 4 shared image data buffers
my @flags :shared = (0) x 4;    ## 4 shared 'image ready' flags

sub loadJpg {
    my( $host, $url, $no, $dataref ) = @_;
    next if $flags[ $no ];  ## If the flag is still set do nothing

    #load the image
    my $sock = IO::Socket::INET->new(PeerAddr=>$host,Proto=>'tcp',Peer
+Port=>80,);
    return unless defined $sock;
    $sock->autoflush(1);
    print $sock "GET $url HTTP/1.0\r\nHost: $host\r\n\r\n";
    my $status = <$sock>;
    die unless ($status =~ m|HTTP/\S+\s+200|);

    my ($grab,$jpeg,$data,$image,$thisbuf,$lastimage);
    while (my $nread = sysread($sock, $thisbuf, 4096)) {
        $grab .= $thisbuf;
        if ( $grab =~ s/(.*?)\n--ZoneMinderFrame\r\n//s ) {

            $jpeg .= $1;
            $jpeg =~ s/--ZoneMinderFrame\r\n//; # Heh, what a
            $jpeg =~ s/Content-Length: \d+\r\n//; # Nasty little
            $jpeg =~ s/Content-Type: \S+\r\n\r\n//; # Hack

            #$data = encode_base64($jpeg);
            $data=$jpeg;
            ## copy to the appropriate shared buffer
            $dataref->[ $no ] = $data;

            ## Set the appropriate 'image ready' flag
            $flags[ $no ] = 1;
 
            $lastimage->delete if ($lastimage); #essential as Photo le
+aks!
            $lastimage = $image;
            undef $jpeg;
            undef $data;
        }
        $jpeg .= $1 if ($grab =~ s/(.*)(?=\n)//s);
    }
}

## Start the threads passing 
## The host, url, buffer/flag number and buffer reference
my @threads = map{
    threads->new( \&loadJpg, $host, $urls[ $_ ], $_, \@data );
} 0 .. 3;

my $stop = 0;
my $mw = MainWindow->new(title=>"Cams");
$mw->minsize( qw(640 480));
my $top = $mw->Frame()->pack(-side=>'top');
my $bottom = $mw->Frame()->pack(-side=>'bottom');

## Use an array, indexed by passed number
my @photos =  (
    $top->Label()->pack(-side => 'left'),
    $top->Label()->pack(-side => 'right'),
    $bottom->Label()->pack(-side => 'left'),
    $bottom->Label()->pack(-side => 'right'),
);

$mw->Button(-text=>"Stop",-command => sub { $stop=1; })->pack();

## Set up a regular callback in the main thread that
## a) checks the flags for each image 
## and if it is set
## b) Locks the data
## c) Encodes the data
## d) Creates a Photo object from it
## e) Sets it into the widget
## f) Clears the flag ready for the next
$mw->repeat( 1000, sub{
    for my $n ( 0 .. 3 ) {
        if( $flags[ $n ] ) {
            lock( @data );
            my $data = encode_base64( $data[ $n ] );
            $image[ $n ]->delete if $image[ $n ];   ## Addendum: 
            $image[ $n ] = $mw->Photo( -format=>'jpeg', -data=>$data )
+;
            $photos[ $n ]->configure( -image => $image[ $n ] );
            $flags[ $n ] = 0;
        }
    }
} );

MainLoop;
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