I wonder what Google thinks about this. Seeing as they discontinued their text translation API because of 3rd party abuse, I wonder if this would suffer the same fate if it gets popular.
Best recommendation is to use Nuance's HTTP Api http://dragonmobile.nuancemobiledeveloper.com/public/index.p...
It's not free, but it's at least it's guaranteed for commercial use.
I don't work for Nuance, but my startup uses their products now - and the accuracy and speed are great. The documentation is pretty horrible, so feel free to reach out w/any questions on the program/usage/etc.