I just created and submitted to mycroft, Mozilla/Firefox search engines plugins archive, a plugin to search for Drupal 5.x apis at api.drupal.org.

Unfortunately, while I was submitting the plugin, I forgot to change one value which let the plugin search into 4.7 documentation instead of 5.x.

Mycroft does not have an editing feature then I was not able to correct the problem.

Then I had to submit the plugin again which now works.
So.. if you search for drupal api at mycroft you will get also the broken version.

The correct one is the link titled Ref: 15333 (drupal_api_5). (Put your mouse over it and the title will appear)

UPDATE: I also created a search plugin for Drupal 6.