_config.yml

authors:
  hanzou:
    name: Hanzou Hattori
    display_name: Hanzou
    gravatar: c66919cb194f96c696c1da0c47354a6a
    email: hanzou@company.com
    web: http://company.com
    twitter: company
    github: hhattori
  jorgen:
    name: Jörgen Mortensen
    display_name: Jörgen
    gravatar: 12e480a364a5c19214f99b4dfe9a11d5
    email: jorgen@company.com
    web: http://company.com
    twitter: company
    github: jorgenm

post.html

{% assign author = site.authors[page.author] %}
<article class="entry">
  <header>
    <p class="date">
      <span class="month">{{ page.date | date: '%b' }}</span>
      <span class="day">{{ page.date | date: '%d' }}</span>
      <span class="year">{{ page.date | date: '%Y' }}</span>
    </p>
    <h1>{{ page.title }}</h1>
    <p class="byline">
      by {{ author.display_name }}
    </p> <!-- /.byline -->
  </header>
  …
</article>

yaml-front-matter.yml

---
layout: post
title: "Migrating from Tumblr to Jekyll"
author: jorgen
tags: [ Tumblr, Jekyll, tutorial ]
css_classes: [ permalink ]
---