So I counted my fingers and toes (including thumbs) and I still can't count how many people have asked me about the possibility of having the functionality of Tarmac (automatic merging) built into Launchpad. The short answer is "No." The long answer is also "No."

There are many reasons for this. The first one I can come up with is the test suite. Sure, you can automate the merging of branches, but c'mon, what's the point of automating it if it's just going to propagate breakage? So the running of tests is relatively essential in automated merging. Elliot got a patch into Tarmac the day after 0.1 to do just this, and I have recently refactored it to work as a plugin. So, for instance, Entertainer can have approved merges, and Tarmac will check out a fresh copy trunk, merge in the branch, and run the tests. If the tests pass, it lands, if not, then the test output is added to the merge proposal. The problem with this is that many test suites take a very long time to run. Others may be quite CPU intensive. As one can imagine, that can require a lot of hardware.

Now, think of test suite you're running. Who wrote it? Not the Launchpad folk. PQM has put a lot of effort into making sure that the tests are run in a sandbox, and not in an environment that would have security implications. In fact, I've put a lot of thought into how to run the tests in a chroot environment for the Tarmac instances I maintain. This is quite a complicated setup.

Lastly, you may need a build environment. Maybe you're working in Windows, or you need a database, etc. These things are pretty specific to an environment. The possibilities are endless. This also has huge hardware implications.

Bottom line: Provide your own test environment, run Tarmac on a cron, make your development team happy.

Side note: I'd love to see if Tarmac would run on Windows. I don't have any Windows machines around, so (for bonus points) would someone please volunteer to try it there? Update: John Meinel was awesome enough to hack on Tarmac enough to get it running on Windows, and the branches have been submitted for review. This means that Tarmac 0.2 will have Windows compatibility as well. Woot!