We have been quietly working on a solution to auto-grade the content of student speaking. Super Moodle developer Gordon Bateson has lent his expertise on the questions, and they are starting to work quite well. Our EnglishCentral and ReadAloud plugins already evaluate a student speaking. And we hope the new autograde speaking questions will complement them well.
You can try a very simple quiz on the Poodll Demo Course. Be sure to use Google Chrome, though in future we will support more browsers.