This is a good project. I think lots of people will be coming to drupal with HTML, CSS and graphic/web design skills and will want to make great themes and site designs. I take it this project will be focusing on letting designers do this without getting too deep into the drupal theming system via php-template engines. I think this is good because we should not expect designers to learn php just to make a drupal theme. I think a .make file which would provide a easy installation profile is a great idea. Also documentation here will be crucial.

In my opinion why waste energy on drupal 6. If we start planning now I am sure a Release Candidate for D7 will be out, and designers will embrace changes in the UI on D7.

In my opinion the idea here must involve base themes (fusion and zen come to mind). Even bartik is a nice default theme in D7. My toolkit definitely involves a couple of modules: SWEAVER and SKINR. Sweaver works on D7, Skinr is under development and currently doesn't work with D7.