Once again, I am slated to present general Object-Oriented techniques at DrupalCon. It's an important topic; sadly a large number of Drupalers don't really "get" OO programming, but Drupal 7 is starting to make heavy use of OO. There are also an enormous number of places in Drupal where a more Object-Oriented approach would make the code vastly cleaner, simpler, and faster, if only more people thought to approach it from that standpoint.
Of course, the question is how to target such a session. I don't want to talk over people's heads, but I also don't want to waste your time with "this is a mouse"-level material.