Here is something worth looking at:

SoundHound just announced Hound, a new personal voice assistant with quite astonishing results.

It will be available on Android and iOS, but what's more important, they also announced Houndify, a cross-platform ("iOS, Android, Windows, Unix, Raspberry Pi, and others.") interface for developers to integrate in their apps.

I am not sure about the pricing (if there's any), but seems worth to look at, at least as an option for those who wouldn't mind getting the results from a 3rd party.