The Von Kempelen vk Voice system provides professional-grade text to speech services using their network of "human talkers." In a nutshell, they transform text into spoken words using a higly qualified Mechanical Turk workforce.
The service can accept text in a wide variety of formats including RSS, email, and web forms, and they are ready and able to support other formats as the need arise. They plan to provide this service in a wide variety of languages; qualifications will be posted soon. They also offer text translation services and custom Mechanical Turk application development.