After taking a photo session I thought it would be cool to have some more shiny Image functionality in octopress. FancyBox seems to be bleeding edge, so I did have a look into it.
Devin Weaver had a solution which looked good, but it's some kinda broken with recent octopress installations and I wasn't able to trace the problem down. Even this fix is broken for me.
Anyways ... the Slash Theme has build in fancybox support. Erv Walter provided octopress customizations which includes fancybox. After having a closer look, this seems worth.
The following modifications was made, maybe you need to adjust the URLs for JQuery and Fancybox Javescript Code and Stylesheet:
{% include_code source/javascripts/fancybox-integration.js 2012/12/fancybox-integration.js lang:javascript %}
{% include_code source/_includes/custom/head.html 2012/12/head.html lang:html %}
{% include_code source/_includes/custom/after_footer.html 2012/12/after_footer.html lang:html %}
{% include_code octopress_fancybox.diff 2012/12/octopress_fancybox.diff lang:diff %}