All subjects below this post's menu item should be considered outdated.
Updated notes are under menu heading "drupal" > "drupal notes" without the antique.
The outdated notes below are essentially hidden from search engines. After you have clicked "drupal atiques", the menu items for obsolete notes expands with the full list. These are technical notes for Drupal 6.x. and modules from 2009 to about 2010. The version number is mentioned at the top of each note.
The notes may still contain some useful content, and apparently there are still a number of external links to them. They remain on site, in the antiques section. Don't kick up too much dust!
This month I enabled the core statistics module and I'm positively surprised about the number of visits that these older notes are getting. It's a great motivation to speed up on updating them. I'm working on a new multi language site so I'll start with that.