UPDATE: As from the comments below and various emails I have received, this might be an isolated issue related to my combination of code and plugins. Many people continue to use Feedburner Feed Replacement without any issues.
If you have been using the Feedburner Feed Replacement Plugin originally from Steve Smith, and have not checked your feeds lately, it might be worth a few minutes of your time to do so. Just browse to your blog’s feed address (http://yourblog.com/feed/) and if you are redirected to your Feedburner feed, you are fine. Otherwise you need to uninstall the Feedburner plugin and get something else.
In all honesty, I have not had the chance to figure out why the plugin stopped working but I did some research on the web and no-one seems to have noticed the problem. It might be an isolated case where my configurations or combination of plugins on this blog is causing the issue but I highly doubt it. The Feedburner plugin page says that the plugin works with WordPress 2.5 and below. I replaced that plugin with the one from John Watson and everything seems to be working fine again. The feed counts might not go up right away (we are putting more effort and resources into writing better articles and publishing more useful news for you) but I feel better knowing that everything is kosher on the feed side.
Do you use the Feedburner Feed Replacement Plugin? Was feed broken? What other Feedburner plugins do you use and like?