I’m actually really liking the new ICS-style action bar dropdown, like used in the Gmail and calendar apps. Seems to do roughly the same in a more consistent manner.
The upside to this approach is that you can still use the home as up behavior on a subscreen if you like. I don't see why the G+ app didn't do something like this considering there are only 6 main sections in the app and they continue to use home as up in some subscreens.
