Richard Bates has a new post to the Flexandair.com blog about the new AMF support that the latest Zend Framework version (1.7) contains - the Zend_Amf component.
To get started with Zend_Amf, you'll first need to download Zend Framework 1.7. To do that, go to the Zend Framework download page and select the 1.7 release (near the bottom of the page). Alternatively, you can download only the components required for Zend_Amf here. This is the current build from the incubator (SVN), so its no more stable than the full release, just smaller (128 kb).
He also mentions some of the "pitfalls" that he had when trying to get it up and working, specifically with the class mapping and defining RemoteObject parameters in the code rather than an external XML file.