This is a must read :) http://www.boxesandarrows.com/archives/ implementing_a_pattern_library_in_the_real_world_a_yahoo_case_study.ph p
Wow - we could use this pattern.module on drupal.org. Perhaps Yahoo will share the source with us? If anyone has a relationship with the article authors, please ask. If not, it wouldn't be too hard to reproduce. Also, the article authors probably can give us feedback on the UI of drupal itself.
I believe Roland has some friends in Yahoo, and he's already made it known to them that we'd be happy to help them with Drupal in any way (we noticed this article/posted about it a couple of weeks back).
Since the date on this article says april 29 (which was last friday), you should really have good inside sources :) Goba