I used to work at Google. Its a big company, composed of almost 10^5 employees today. In my experience, they can be trusted to adhere to the letter of their agreements; no more and no less. That's not as bad as it might sound. Plenty of companies consider their contracts to be far more mutable than Google did while I was there.

But it does mean that you can't take any individual employee's word about what they are doing today. Individuals change. Managers change. People come and go. A fundamental part of the company mythos is that you as an individual know more about what goes on in the company than you really do. So unless you are acting in an official capacity to speak for the gmail and calendar teams, you should hush.

If the letter of their agreements permits GOOG to use your data for <X> purpose, then as a user of the service you should assume that they are.