in-page text-to-speech

Hi all, 

I have encountered some sites recently that use in-page text-to-speech.
ReadSpeaker and BrowseAloud are two that spring to mind. I'd really
appreeciate any thoughts about these kinds of supplemental technologies,
particularly with regards to meeting the WCAG 2.0 conformance requirements.
An example of one of these TTs implementations is at:
http://www.health.vic.gov.au/news/new-laws-protect-victorians-in-supported-r
esidential-services.htm

Cheers,
Adam