The 4.7-1.0 version was originally developed by JanRain to implement OpenID consumer support in Drupal using the JanRain PHP OpenID and Yadis libraries. The 4.7-2.x branch was developed by James Walker and Rowan Kerr to support OpenID 2.x, and include a server and a client component.
The 5.x version only includes client support and is a backport of the 6.x version of this module which is available in Drupal core, and is therefore not to be found here. The server component lives on in the OpenID Provider module at http://drupal.org/project/openid_provider and in the OpenID Attribute Exchange module at http://drupal.org/project/openid_ax.
Find out more about OpenID at openid.net.
Important: the update function in OpenID 5.x-1.4 malfunctions. If you updated to 5.x-1.4, install OpenID 5.x-1.5 instead and run update.php.