This is a notice to all add-meta-tags plugin users.
If you upgrade WordPress to the latest 2.1 release, it is highly recommended to also update the add-meta-tags plugin to the latest version (v0.9 at the moment of writing), so to avoid experiencing empty description META tags in single post view, the consequences of which are unknown.
WordPress 2.1 contains fixes which affect the
get_the_excerpt() function's operation outside the loop, which is used this plugin, resulting in empty description meta-tag. Posts in which a custom excerpt or a "description" custom field has been set are not affected.
The Add-Meta-Tags latest version is 0.9.