WordPress MU is a unique WordPress product. Plugins and themes are controlled by a central system administrator. So unlike the single-user version of WordPress, individual MU bloggers cannot upload their own plugins and themes, only select from the ones made available by the system administrator. While WordPressMU users are blogging with a limited version of WordPress, and currently are able to choose from a list of included WordPress Themes and have little customization, there are still a lot of benefits. Designing Themes for WordPress is pretty wide open since each Theme is a self-contained package. The files and styles are all there, and little else is needed - to a point. The rest is up to the user to tweak with. With WordPressMU, the options are limited to choices, not tweakability. When it comes to designing your styles or Themes for contests and public consumption, there are a few things you should take into consideration. These are not hard and fast rules, they are more guidelines, on how to make your Theme the best it can be before exposing it to the public.