Java Speech
In case you have not seen these before I wanted to add some links to some cool Java Speech systems that are currently in development.
FreeTTS is an opensource JSAPI based TTS engine that is moving along well. Performance is not too bad and the audio quality should be ok if you develop a proper voice package.
Sphinx-4 is a Java port of the Sphinx ASR engine. Performance is inline with the C++ version and Sun has a few engineers working on the project full time.
If you are developing java based speech systems they are definitely worth a look.