I think you mean Octopress based on Jekyll, not WordPress. Before switching away, I got close to storing webmentions in Jekyll _data files. I still get twitchy thinking about Jekyll. Someday I think I’ll return.
Oops, good catch! I’ve updated the post.
I store my webmentions in Jekyll _data files, as well as reply contexts for reply posts like this one.
I’m pretty close to considering them “stable enough for public use”, but being unfamiliar with the process of releasing, maintaining, and supporting a Jekyll plugin, I am holding off at the moment.