hi there ;-)
i receive the following error ->
[18-Jul-2012 23:17:41] PHP Fatal error: Call to undefined function apply_filter() in /path/to/wordpress/httpdocs/wp-content/plugins/addthis/addthis_social_widget.php on line 477
but i only do receive this error on sites with the addthis sidebar widget enabled.
all other sites with the addthis above or below the articles / posts are fine!
any help would be more than appreciated ;-)