The large drupal's main site (www.drupal.org) was updated to version 6 last month. I finally managed to find time to move viggie.com from version 5.
It is a relaunch & slightly different from updating from version 5 to 6. The layout is changed & the presentation is improved. Based on my experience I will write soon on the steps that were needed to update Drupal site from Version 5 to 6.