From looking at Google's privacy policy for this product, it seems to me that if I have a file called all-my-deepest-secrets-fears-and-desires.txt stored in Google's cloud, then nothing stops Google from sharing what they learn from this file as long as it is "non-personally identifiable information". That sounds like they can do whatever they want, as long as they don't attach my actual name to it.
The irony of "non-personally identifiable information" is that there is no such thing. Just show me your regular everyday travel destinations, i.e. mostly home -> work -> home and I will identify you. Not to mention card purchases (Google bank accounts to the rescue!) that contain more information than you know about yourself.
Or if you are a software engineer, show me enough of your source code with file names etc. (including your commercial work) and I might be able to match you against the full LinkedIn database for example, although I probbaly won't be able to automate this one. Etc. etc.
Nothing is ever completely anonymous unless you get to the level of elementary physical particles which as we know don't have an identity :)
