Larry Garfield Explains Object-Oriented Programming
Larry Garfield of Palantir.net talks about the differences between Procedural Coding and Object-Oriented Programming as well as the vertical extensibility of OOP.
Larry was very involved with the Go PHP 5 initiative to encourage hosting providers to upgrade from PHP4, and as a result of the success of this effort, Drupal 7 will be the first release that will require PHP5. For the first time, Drupal will be able to use the more evolved Classes and Objects features of PHP5.
Larry gave a Drupalcon presentation on Objectifying Drupal: An introduction to OOP and has some strong thoughts on how the core of Drupal should and should not use OOP.
You can read more about his Handlers proposal that he mentions here and get the latest updates on it from here.