Running django migrations on multiple databases simultaneously
First, I'd really look (very hard) for a way to launch a script that does as masnun suggests on the client side, really hard.
Second, if that does not work, then I'd try the following:

Configure on your local machine all client databases in the settings variable DATABASES
Make sure you can connect to all the client databases, this may need some fiddling
Then you run the "manage.py migrate" process with the extra flag --database=mydatabase (where "mydatabase" is the handle provided in the configuration) for EACH client database

I have not tried this, but I don't see why it wouldn't work ...
We are developing a b2b application with django. For each client, we launch a new virtual server machine and a database. So each client has a separate installation of our application. (We do so because by the nature of our application, one client may require high use of resources at certain times, and we do not want one client's state to affect the others)
Each of these installations are binded to a central repository. If we update the application code, when we push to the master branch, all installations detect this, pull the latest version of the code and restart the application.
If we update the database schema on the other hand, currently, we need to run migrations manually by connecting to each db instance one by one (settings.py file reads the database settings from an external file which is not in the repo, we add this file manually upon installation). 
Can we automate this process? i.e. given a list of databases, is it possible to run migrations on these databases with a single command?