We just finished upgrading drupal.org to CVS HEAD, the code that will become Drupal 4.5.0. So in good Drupal tradition, we (developers) get to eat our own dog food again, and you (users) get to see and test that latest changes.

This marks a significant upgrade, yet most of the changes will only be visible to this site's administrators. We are still fine-tuning the site, but please let us know if you find anything out of whack.

For those who are faced with the task to update their Drupal 4.4 sites, here is what drupal.org's upgrade process looked like:

1. I made a backup of both the drupal.org database and the Drupal source code used on drupal.org.
2. I knew that because of the theme system changes, the upgrade would replace the Xtemplate/Pushbutton-specific mission statement by the default one. So I went ahead and reworked the default mission statement up-front while I still had the old one handy. Note that drupal.org's new mission statement is both shorter and less technical than the old one.

   Similarly, I knew that for the same reason Xtemplate's primary and secondary links would get lost. The upgrade script still needs to be modified to migrate these settings for you, so for now, I made a copy of them so I could restore them easily.

3. Next, I went to the administration pages and disabled all contributed themes and modules. This isn't strictly necessary, but make the upgrade process less prone to error. It allowed me to upgrade core without having to worry about contributed modules and themes. Some of these might not be compatile with CVS HEAD yet. Once core was upgraded sucessfully, I upgraded the contributed modules one by one.
4. Before upgrading our Drupal copy, I logged in as the user with user ID #1. This will make running the database upgrade script easier.
5. Because some files got renamed and other files got removed or reorganized compared to Drupal 4.4, I did not want to copy the new sources over the existing sources. Any left-overs might cause breakage so it is best to remove your old Drupal copy and to start fresh. Since we are using CVS to grab and maintain our Drupal copy, this was a non-issue: a CVS update removes such left-overs.
6. Once the Drupal sources were updated, it was time to update the database. I went to http://drupal.org/update.php and manually created the users_roles and locales_meta tables as per the instructions. Unfortunately, the upgrade script can't create these tables for you. Next, I ran the database update script and went to the administration page.
7. I didn't had to make many configuration changes. Nearly all time was spent configuring the new input formats, and reconfiguring the drupal.org theme (bluemarine).

Hope that helps.