ZFW is the counterpart to Zend_Feed_Reader (as if that wasn't obvious). It's purpose is to, once again, offer an alternative to the current Zend_Feed component using similar principles to those applied in Zend_Feed_Reader. [...] Which brings us to upcoming proposal number two, the colourfully named Zend_PubSubHubbub! Or Zend_Feed_PubSubHubbub depending on which name is most appropriate. To explain, PubSubHubbub defines a protocol where any subscriber (that's you) can subscribe to a hub server which notifies you when any feed you want to follow has changed.

He gets into a bit more detail and explains some features for each component and how they'd integrate with a few of the other modules in the framework. You can find the proposal for the Zend_Feed_Writer here and the Zend_PubSubHubbub proposal here.