Actually, I'm not so sure its a acquihire. Google has very recently announced a bunch of cloud machine learning products:

https://cloud.google.com/products/machine-learning/

* Cloud Vision API - Upload an image, and it will tell you what is in it

* Cloud Speech API - Upload a wav and it will transcribe it

* Natural Language API - Parse sentences, extracts entities, sentiment and syntax

* Cloud Translate API - Translate from one language to another.

Api.ai would make a great bullet point to add to the end of that list!