If you got a chance to play a Windows phone 7, you can try out speech feature in it.

It has three cool speech features: voice search, voice activated dialing and start application by command.  

In these scenerios, Zira TTS will use to speak the text back.   I hope you will love it.

More news about speech for phone 7.

http://www.microsoft.com/presspass/presskits/speech/videoGallery.aspx

http://www.microsoft.com/presspass/features/2010/aug10/08-03gamechangerfea.mspx

http://www.pcworld.com/businesscenter/article/202560/windows_phone_7_to_excel_on_speech.html