Zend_Service_Twitter looks like it will be fairly comprehensive, but it's not in the core yet and is probably a little overkill for my simple use case. I then had a look at Zend_Rest_Client, which seemed to confuse me. I couldn't actually get it to add the parameters I wanted to the call, I guess it's better for interacting with Zend_Rest_Server or fully restful APIs.

He opts for the Zend_Http_Client component and includes the simple fifteen line script to make the connection and post a new update.