Since we released Qt under open governance on qt-project.org, there was always one piece missing. The Qt 4 repository was so far still handled in the old system. This was done as a simple prioritization, to get the parts of Qt that we considered most relevant for the development community out first.
The main problem has been the additional work required to integrate Qt 4 with the continuous integration (CI) system used on qt-project. Thanks to the efforts of Sergio, Rohan and others this has now been (mostly) solved. We run the full CI setup (that includes both compilation and running the test suite) on both Linux and Mac OS X for Qt 4.8. On Windows we currently only run compile tests, running the automated tests on Windows is coming soon.
You can now find the Qt 4.x repository on codereview. Pushing and reviewing changes works the same way as for Qt 5.
Approvers and Maintainers are the same as for the respective areas in Qt 5, but it should be noted that I don't expect a lot of further development to happen in Qt 4.8. The focus here should be on bug fixes, and patches should be reviewed with this in mind.
The Qt 4.6 and 4.7 branches are not CI tested, so extreme care should be taken when submitting to these branches, and I'd like to see a review from a Maintainer for any change going in there. Changes in these branches should be limited to security issues and severe bugs that can't be worked around in user code.
Any pending merge requests in gitorious should be resubmitted through gerrit, as we'll close merge requests on gitorious and turn the repository there into a readonly copy.