Finally, a stable release of GD Star Rating plugin is available:
GD Star Rating 1.0.0: Halloween Edition
GD Star Rating is post, page and comment rating plugin for WordPress. Plugin supports different image sets, rating moderation, vote rules, time restricted voting, templates, trend calculations, has a widget build in and shortcode support.
Detailed info: http://wp.gdragon.info/2008/11/01/gd-star-rating-100/
User Guide: http://wp.gdragon.info/download/12/
Plugin Download: http://wp.gdragon.info/download/8/