Because http://drupal.org/project/Modules/name is cached on drupal.org, anonymous users will see only one version of this form (filtered by 4.7.x or 5.x or whatever) and can't change it.
The way to fix this is to make separate URLs for each list, like http://drupal.org/project/Modules/4.7.x/name. This gives the extra added bonus that these pages could be bookmarked.
Because you're drilling down by version, the "top" tabs should be:
Drupal 4.6.x | Drupal 4.7.x | Drupal 5.x | All
And the "sub-tabs" should be:
Browse by category | Browse by name | Browse by date
I might try and take a stab at implementing this.