This week Google Apps for Education administrators were given the option to create private Google Play channels. In a private Google Play channel you can restrict distribution of apps to just the people within your domain. It's important to note that this only works for apps that are developed by people within the domain. You cannot use it to push 3rd party apps to users of your domain. Google Apps domain administrators can find directions for creating a private Google Play channel here.
Via Frédéric DEBAILLEUL