How I got 0.4 alpha3 working on debian lenny

Hi! Thanks sharing your experiences. Fellow Debian Lenny user here :)

As described in the install.txt documentation (but not reminded in the installer that I noticed) add the below to /etc/sudoers:
aegir ALL = NOPASSWD: /usr/sbin/apache2ctl

This is instructed in the web-based installer, with the appropriate command given as an example in the 'How do I configure this' dropdown.

Had to redo the grant statements for the aegir mysql user:
GRANT ALL PRIVILEGES ON *.* TO 'aegir'@'localhost' IDENTIFIED BY 'mypassword' WITH GRANT OPTION;
GRANT ALL PRIVILEGES ON *.* TO 'aegir'@'127.0.0.1' IDENTIFIED BY 'mypassword' WITH GRANT OPTION;
FLUSH PRIVILEGES;

This is instructed in the web-based installer, with the appropriate command given as an example in the 'How do I configure this' dropdown. The intention is to create a separate user 'aegir_root' which is a mysql 'superuser' capable of creating new databases on your system.

Needed to change the directory ownership and permissions for aegir to allow www-data (webserver user) to operate properly: (the www-data or $WEB_GROUP user was not given proper permissions by installer)

www-data user does not need to be the group of the entire contents of /var/aegir, only of directories which it needs to be able to write to (i.e the files directory), and temporarily of the main aegir site's settings.php before you finish the web-based installer. You mention the installer did not change the permissions properly where needed. Per this bit in the install.sh

chmod 2770 sites/$AEGIR_DOMAIN/files
chgrp $WEB_GROUP sites/$AEGIR_DOMAIN/settings.php
chgrp $WEB_GROUP sites/$AEGIR_DOMAIN/files

Were there any errors given that made you notice the permissions hadn't been changed?

chmod g+x /var/aegir

If you're not getting a default 755 permission on directories in Debian Lenny, then perhaps your umask is set to be something else non-standard.

./drush/drush.php dl drupal <-- this file doesn't exist anymore in 0.4 (the instructions need to be updated to reflect now using drush make)

This file should indeed exist if you are executing that from within /var/aegir . Drush2.1 still has drush.php .

Drush_make is not required to build new platforms - it is used to build the aegir frontend because it is capable of grabbing extra dependencies via the install profile's makefile. In my opinion, unless you are deliberately generating 'builds' as platforms that have special requirements, install profiles etc, it is just as quick to use 'drush dl drupal'. We can't really change the instructions to use drush make each time you make a platform, because the make file and the command to generate it is likely to change each time, and vary wildly between users, once people start to use drush_make more. 'drush dl drupal' is still the generic, standard way one can download a copy of Drupal core using Drush, and we can rely on that not to change.