As a Drupal administrator, Drush aliases is a tool I cannot live without. It provides a way for me to connect to any Drupal site on any environment and run drush commands. The only requirement is that I have SSH access to those servers.
Anyone who has worked with Drush and Drupal multi-site should be aware of the @sites shortcut, which allows you to run Drush commands on all your sites as a single command. However, the @sites shortcut is the same format as the Drush remote alias format, @example, which causes Drush to not recognize the multi-site shortcut. So for instance:
$ drush @example.prod @sites cache-clear all
Won’t work. Instead use the following simple fix:
$ drush @example.prod "@sites cache-clear all"
And now Drush will pass everything within the quotes to the remote server.
Hope this helps!!
Update: Due to a bug with how the uri is passed to SSH, you will need to use the latest dev version of Drush 7