I just updated the plugin on a WordPress 3.3.1 install and ran across a few annoying warming messages caused by an unquoted variable name in line 604 of sharethis.php. Here is a patch you can apply. Just replace the st_menu_items function with this snippet and you're good.
function st_menu_items() {
if (ak_can_update_options()) {
add_options_page(
__('ShareThis Options', 'sharethis')
, __('ShareThis', 'sharethis')
, 'manage_options'
, basename(__FILE__)
, 'st_options_form'
);
}
}