Zend_Feed has always been a thorn in my side, so I'm pretty satisfied with myself (egomaniac!) now that I am building up what I like to consider a pretty good set of components for consuming and creating feeds without needing a hastily kicked together DIY processor on top of Zend_Feed. [...] Zend_Feed_Reader was an attempt to bring more sanity to the area. It largely bypassed the issue with simple access by standardising on a getter style API.

As the component evolved, several issues of its own popped up and Padraic has done some fine tuning of the code to make things even better. The Zend_Feed_Writer component was created to make a more flexible Zend_Feed_Builder and handle some validation of the content and structure of the information to be generated. Because of the features this new component brings, the Zend_Feed_Reader was enhanced with four new updates to bring it up to par:

• Extend support to the whole of the Atom 1.0 specification.
• Extend the API coverage overall.
• Implement Array style access.
• Standardise API return types using ArrayObjects.

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.