Thanks folks.

Trouble was I did not really understand Apache's document structure. I do now :)

I moved the file to a temp directory and accessed it from there. Now it looks (and works) like this:

#!/usr/bin/perl -wT
use strict;
use CGI;

my $cgi = new CGI;

print $cgi->header();
print $cgi->start_html(qq(Image practice));
print $cgi->img({-SRC=> '/temp/nelo/gnuplot2.gif', -ALIGN=> 'left'});
print $cgi->end_html();
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