When the site gets too busy, the infrastructure team sometimes disables the built-in search function. In an effort to cut down on the number of posts reporting this, I am linking to all the recent ones here and promoting this.
When it's down, you can always use Google. Just put "site:drupal.org" in your query.
http://drupal.org/node/270417
http://drupal.org/node/272571
http://drupal.org/node/271612
http://drupal.org/node/269992
http://drupal.org/node/271694
http://drupal.org/node/271936
http://drupal.org/node/272208
http://drupal.org/node/270705
http://drupal.org/node/272506
http://drupal.org/node/255841
Michelle
Note: Because I noticed several comments about use of the throttle module, I've updated this post to clarify that the search module on Drupal.org is not disabled automatically by the throttle module. At this moment, Drupal.org does not use the throttle module. --David Strauss, Drupal.org Infrastructure Team
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