I was able to dig up the files I used to install Wordpress on Zen Cart. I had installed 1.4, but had forgotten this as it was a while ago.

So, reinstalled WOZ once more, but have the same problem. Blog is working fine on its own (http://www.halfletterpress.com/blog), but it won't show up in my store (http://www.halfletterpress.com/store/?).

The titles will appear (e.g. http://www.halfletterpress.com/store/?p=673), but the center column has nothing in it.