This section of the site is generated completely by the plugin, it's a separate WordPress install to the main site just for grabbing related news.
None of the categories work when clicked on, try the early day motions one for example.
WordPress 3.8.1 not a 3.8.1 issue per se, just updated from 3.6 and the issue was present before the update, not sure how long it's been a problem (not been checking the site).
Version 2013.0504 with Add Attribution for FeedWordPress Version 2009.0730
Think the latter plugin has been updated, so just about to update it.
Deactivating both plugins fixes the issue. Deactivating just the attribution plugin doesn't fix the problem, so it's the main plugin.
Run other plugins, but I own over 100 domains with WordPress and use those plugins on lots of them and no issues with categories, so highly unlikely Akismet, Broken Link Checker, WP Super Cache and a couple of others would be the issue. I develop the theme and run it on a lot of sites, so again highly unlikely to be the problem.
This is the only site I use this plugin on, so no other examples to compare.