Chrome provides it to in-browser applications via the Web Speech API. However, Google doesn't allow any other browsers or services to use that endpoint (except for Chromium development, and that only with an extremely limited quota).
There's an API for it on Android as well that app developers can use.
I've seen Android Wear apps on the Play Store that utilize it as well.
50 API reqs/day. Very small quota, which is sad, because it is over twice as good as the next best competitor I've found (IBM Bluemix).
That is really too bad. I'd have loved an offline application that could reliably recognize my speech, like the Amazon echo but not connected to the Internet.
Yeah good luck with that. I'd say Google's voice recognition is one of their most valuable things. Siri is the nest best but that isn't really close.
It's a shame they haven't done more with it really.
I don't know about Siri, but there are various means to integrate commands into both Google speech recognition (at least on Android) and Amazon Alexa (Echo). Amazon at least is looking to get third-party devices integrated. Probably not what you were hoping for in either case, but it is enough for a lot of potential uses.