Some kind of "off the record" mode would be invaluable for voice interfaces. Hell, it would be nice if there was a check box under the Google search box as well, but I imagine Google would never make it too easy to avoid their data mining. I feel like we never had the proper privacy conversation we needed to have with companies like MS, Google, Facebook, etc. I think some level of easy to use yet strict segregation between what I consider my public life and my private life should be cooked-in, and enabled by default, into all this software.