What the plugin does is allows visitors to authenticate using any OpenID account (Google, Yahoo, or AIM) and then comment on posts. When a visitor authenticates, it automatically creates a WordPress account. After a visitor posts content or comments on a post, the information will appear in the Google Friend Connect activity stream. The plugin features (colors, size, labels, etc.) can also be customized to suit.
A tip of the hat to Chris Crum for sharing this news.