Since Hyperbole and a Half is Creative Commons licensed (CC-NC-ND), it looks like its licensing requirements would be satisfied by attributing the original source ("Proper credit includes a prominent, easily visible link to the source of the material you want to use...")[1].

I think making sure that images in your blog post are properly licensed is difficult [2], but on the same level of difficulty and importance as determining a license for a software project [3].

[1]: http://hyperboleandahalf.blogspot.com/p/faq_10.html

[2]: I have personally had issues with this, which I wrote about at http://www.marteydodoo.com/2011/01/19/licensing-is-hard/

[3]: http://www.codinghorror.com/blog/2007/04/pick-a-license-any-...