Roy "yoroy" Scholten has been a part of the usability team since it started to officially form back at Drupalcon Szeged. He talks about his collaboration process with Earl Miles as he helped design the Views 2 User Interface and new design patterns that had to be developed.
He talks a bit about his Drupalcon Paris presentation with Bojhan on a proposed Design Pattern Library for making a consistent user interface within Drupal.
Roy also gives some design tips for module developers like going through a sketching phase to brainstorm the full range of ideas before investing a lot of energy into wireframes. And finally, he talks about getting involved with Drupal as a designer and future ways he hopes to contribute.
UPDATE Roy just posted A user interface design pattern library for Drupal