Tweeted earlier today by Disqus, Disqus 2012 now supports the automatic closing of comment threads.
To set automatic thread closing settings, navigate to your Admin Panel >> Settings page. The setting should be listed on that page.
Now Disqus is officially touting the feature for Disqus 2012 forums, but I think the feature was already in the works because my thread settongs stuck the other day like I set it to, which was 60 days. I disabled the setting for now for another article, and I am currently thinking of thread closing settings in general. So if you wanted to, You could comment on Techman's World's first post.
If you use twitter, it is a good idea to follow @disqus for general stuff and @disqushelp to ask Disqus for help as well as to receive status updates from the Disqus status page.