A few months ago, on a dare, some of us tried to install and run the earliest version of Drupal that we could still checkout from CVS. For my test, I installed Drupal 3.0.2, which was released on 26 November 2001. Note quite ten years old.
What is fascinating about looking at the Drupal 3 release is just how much the Drupal 7 architecture has changed -- and just how much it has not. There are even points in the code where modern debates (such as those over Object Oriented programming) are clearly visible.
So what, if anything, does Drupal 3 have to teach us in 2011? Quite a bit, I believe.