There was an ariticle on web that describes a company with a TTS voice for Hindi. And for all you SAPI devs, the desktop version is SAPI compliant. According the article, "'Vaachak', developed by Prologix Software Solutions, is the first, high-quality, Indian language TTS system, which converts Hindi and English text into natural and pleasant sounding speech."
So, is it any good? I can tell you that the acoustic quality, at least from the demos, sounds a bit compressed and there is certainly some artifacts from concatenation. But still, who else out there has a Hindi TTS system?