I've got a working mod_perl installation on Ubuntu 10.O4. I've done the following things to get it working.

First i've created a file "/etc/apache2/site-available/yoursite" with following configuration:"

<VirtualHost *:80>

        ServerName yoursite
        ServerAdmin webmaster@localhost
        DocumentRoot /var/www/yoursite

        PerlModule ModPerl::Registry

        <Location />
                SetHandler perl-script
                PerlResponseHandler ModPerl::Registry
                Options +ExecCGI
        </Location>

        ErrorLog /var/log/apache2/error.log

        # Possible values include: debug, info, notice, warn, error, c
+rit,
        # alert, emerg.
        LogLevel warn

        CustomLog /var/log/apache2/access.log combined

</VirtualHost>
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Note that i create a virtual host with a given name. To make sure that the site is visible, add a following line in your "/etc/hosts":

127.0.0.1 yoursite.localdomain yoursite
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Now create the directory "/var/www/yoursite", make sure it is readable by user "www-data", and create a file "test.pl" with following content:

use Apache2::RequestUtil;

my $r = Apache2::RequestUtil->request;
$r->content_type("text/html");
$r->print("mod_perl rules!");
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Note i've removed the "$r->send_http_header" line. It is not a valid method anymore under mod_perl2.

Restart your apache server.

This should give, when going to "http://yoursite/perl.pl", the text "mod_perl rules!".

Hope this helps.

Kind regards

Martell