Custom plugin directories in QGIS
A great new feature has been added in revision r15250: Tim Sutton implemented support for custom directories for C++ plugins. The directories are added one at a time, and the next time QGIS is started, it will load both the default plugins and the plugins from the specified directories. The plugins can then be activated as usual from the Plugin Manager.
This is useful for both users, who will find it easier to add third-party plugins, and developers. Another benefit is that there is no need to worry about copying plugins to the correct location after updates.