In the downloads today for Intrepid Ibex, I noticed Espeak was included. Espeak is a speech synthesizer. Click here to go to Espeak's website.
I don't know if it will be released for Hardy Heron or not.
Intrepid Ibex is still in testing stage now, so it is not ready for production machines. If you use it, please put it on a spare machine or spare hard drive. It is due to be released as stable on 30 October 2008.