voceconnect/voce-post-meta — pull request #18 by prettyboymp (2014-09-02 16:07:13+00:00)
Title: Saving a null, false, or empty string

If the value being saved is null, it should delete the stored meta data instead of just updating with an empty value. Updating with an empty value prevents a WP_Query from being able to use the 'NOT EXISTS' meta compare unless all posts have been updated.

My only concern with this is breaking backwards compatibility if code already depends on an empty value.