I checked the latest source out of the git and activated the plugin. But unfortunately this breaks my piwik installation. I get this error message
The following error just broke Piwik (v2.1.0):
Call to undefined function Piwik\Plugins\FeedAnnotation\Piwik_AddAdminSubMenu()
/var/www/piwik.linuxandi.net/plugins/FeedAnnotation/FeedAnnotation.php line 66
This is because it is currently not ready for 2.1 and the market place but there are already issues regarding those problems ( #14 #9 #13)
Closing this as a duplicate of above mentioned tickets. I'll need to clear some time this week to work on those.