I've upgraded this plugin on 2 sites today and both gave errors in place of the widget in the sidebar:
Fatal error: Cannot use object of type stdClass as array in /home/site/public_html/wp-content/plugins/twitter-fans/twitter-fans.php on line 91
And on at least 1 of the 2 (can't remember on the 1st one), it also stopped the site's content from loading. Had to disable. Is a fix coming soon?