On the Trello Android team we have a similar workflow to the web client and server developers. We merge in to a shared development branch when we have a complete feature or bugfix. With git's --no-ff this allows us to see when a new feature was implemented, and when bugs pop up we have a clear list of intersections where they could have been introduced. Our workflow is roughly based on an excellent post by Vincent Driessen, http://nvie.com/posts/a-successful-git-branching-model/.
I'd love to hear more about the Android team's CI tools. What do you build with? What do you test with?
If you can build some kind of SaaS Android CI system, you'd probably make heaps of cash. Android CI is just enough of a pain to do yourself that people would pay for a one click type solution.
We use gradle for building. The actual app is split into two, trello-app and trello-lib. Anything that can be done w/o Android like SQLite caching, API calls, etc., is done in trello-lib which is a plain Java library. It makes the dev cycle much faster since you can write a unit test and run it in a second.
We don't have CI setup yet. For the server we use something custom but will most likely be moving to Buildbot and with that we'll also setup Android CI.
