This is a plugin for Octopress that allows you to use the Facebook Embedded Posts feature just using a simple Liquid tag.
Facebook doesn't let you modify the size of the embedded post at this time, but if that changes, I'll update the plugin.
Download the facebook_embedded_post.rb file into Octopress's plugins/ directory within your site.
{% facebook_embedded_post url %}
{% facebook_embedded_post https://www.facebook.com/FacebookDevelopers/posts/10151471074398553 %}