The Drupal Classified Ads module was initially developed in 2010 as a fork off the drupal.org ed_classified module and evolved separately since then, while ed_classified did not.
The existing ed_classified maintainer recently agreed to let OSInet integrate back Classified Ads into the ed_classified project, as branch 6.x-3.x. This means sites will no longer need to choose and will be able to rely on a single version once again.
This will happen sometime in July 2011, as which point the Classified Ads downloads on the OSInet features server will point back to drupal.org to avoid confusion.