We have just released a new version of our skins and plugins with full support for multi-domain configuration setup. This functionality makes it possible to create different config files for different domains.
Say you run one Roundcube installation that is accessed via two different domains and you'd like to display a different logo image for each domain. Now you can easily accomplish that by enabling the Roundcube 'include_host_config' option and creating two config files for the xskin plugin: one for each domain.
All of our skins and plugins support multi-domain configuration, so you can customize your calendar, signature, advertising, weather, Dropbox, Google Drive, news feed or background according to the needs of the domains through which they are accessed.
You can read this Roundcube documentation page to learn more about the multi-domain functionality,