Unfortunately google is deprecating its feedburner APIs and widgets.
Important: The Google Feedburner APIs have been officially deprecated as of May 26, 2011 will be shut down on October 20, 2012.
It;s pretty sad to see useful services shutdown like this. Also they don't even say it in the feedburner.com site or control panel.
--> when it happens we shall remove feedburner widget from piwik.
Feedburner api will be killed on Oct 20th. a good reminder why NOT to use external third party for services critical such as RSS feed analytics! hopefully one day piwik will offer rss analytics. in the meantime, let's remove the feedburner widgets + all mentions to feedburner from piwik source code.
(In ) Fixes #3404, remove feedburner plugin and allow Piwik to work if plugin folders do not exist.
(In ) Refs #3404, refactor some code into PluginsManager method and fix typo in PluginsManager.
open source feedburner feature request is now tracked in #307