Any ideas as to why the Update Notifier fails to report that a new version of the Wibiya Toolbar has become available? According to my Dashboard, I’m on Version 1.0. The Plugin Directory page for Wibiya Toolbar is on Version: 2.0, Last Updated: 2010-2-23.
http://wordpress.org/extend/plugins/update-notifier/
This is because WordPress itself cannot discover that there is an update (I notice you made the thread http://wordpress.org/support/topic/402552)... I think this is because the readme.txt for this plugin has a Stable Tag of "trunk" (though I don't have access to v1.0 only 2.0) whilst the version number in wibiya.php is "2.0" or (I'm guessing) "1.0". Try getting in contact with the plugin author to fix this.