I've helped recently to unfork the Bluebeach theme (the theme used on Drupal.org and subsites) which was used with different code on drupal.org and groups.drupal.org. So now both sites can use the same source code for their theming. I've also ported the changes to the Drupal 6 port of the theme which was done by Earl Miles earlier, based on the Drupal 5 version. These were all in anticipation of doing upgrades of drupal.org and subsites with the existing theme before going to the next step with Mark Boulton's redesign.
Now Niel Drumm stepped ahead and put the Drupal 6 version of Bluebeach into testing with his port and improvements of the API module, which is used to run api.drupal.org. The new testing site at d6-api.drupal.org is the first Drupal.org subsite to be upgraded from Drupal 5 / to run Drupal 6 (the Drupalcon Washington site was launched on Drupal 6, but it runs under drupalcon.org not drupal.org).
Niel is asking for feedback on a groups.drupal.org post about the upgraded theme and module as well as the new API comparison feature (which I like very much). Since this is the first test site running the theme, helping test just that ensures a smoother upgrade of Drupal.org itself which paves the way for the redesign implementation. Take the new site for a test drive, check out the new features!