Wow, you just cost me about 30 minutes of reading that site...
looks very interesting, though setup isn't quite as easy as it would first seem if you read through the documentation. The Speech-to-Text and Text-to-Speech engines must be downloaded and configured separately from the main app, but otherwise is straight forward. It would take writing a module for it in order to pass along commands to Indigo, but that is definitely doable.
I haven't looked at the licenses, but this could be an interesting project for someone to build and sell as a plug-and-play system to integrate with Indigo. MOST open source software allows you to charge a fee for configuration/distribution, so most likely it would be legitimate. I wonder how many people would be interested. Probably wouldn't make a lot of money, but might could get one free unit out of it or something.
Adam