During the fire side chat at #AndroidDevSummit
the question of the bottom tabs in the G+ Android app came up. The answer from the team was basically "various teams experiment with things, and this doesn't mean this will be incorporated in the material spec" (see the video linked).
The problem though that from the "outside", there are no teams, there's just Google
and most people, including my customers, look at the Google apps as "the Android way".
This is where my problem with experimenting is, especially in this case where a pattern that has been actively called out as "not Android" now shows up in a Google app.
I appreciate that the panel did not shy away from formulating a response during this session anyway.
Now that I have used the new G+ app, I can say that I don't like the tabs; They seem foreign to me, take up a lot of space and function weird (esp. that the last "tab" triggers a sliding panel from the right). I'll hope the G+ team will find a better way for the navigation that they are after.