Seems like Zend framework also following similar approach to what we are doing at Mashup Web Services (seriously I didn't know it before hand). In Zend framework too, they have a extendable Zend_Service class which supports REST as our RestfulService class.
They ships their framework with builtin support to web services such as Akismet, Amazon, Audioscrobbler, Del.icio.us, Flickr, Simpy, StrikeIron, Yahoo! and they plans to add more services later.
I think this is great as a source of inspiration when coming to ideas and planning of our module.